The memory was upgrade from 512Mb SDRAM PC133 low density to 2Gb SDRAM PC133 low density (max for my board according to www.crucial.com).

I hope that is not the RAM you used! I don't think PC133 SDRAM would even fit in a Dimension 3000.

First, if doing upgrades ONLY do ONE upgrade item at a time, make sure everything works and is stable (including rebooting several times) and ONLY then proceed with an additional upgrade item and again verify all is well before proceeding with any additional changes.  Doing all changes at one time leaves you without knowing what device caused the problem. 

Now that you have everything back to original (but that doesn't guarantee that everything is working as it originally did), the first thing to do is run Windows XP "Repair" and see if that gets the OS going again.  All the changes could have "confused" the OS.  Boot from the Windows XP disc but select "Repair".  If this gets the original hardware configuration back working, then proceed as noted with one thing at a time.  You may have to run XP Repair again after the upgrades.

What you are doing is major changes, not just some "minor upgrades".

[quote user="rdbcatcher"] The memory was upgrade from 512Mb SDRAM PC133 low density to 2Gb SDRAM PC133 low density (max for my board according to www.crucial.com).

I hope that is not the RAM you used! I don't think PC133 SDRAM would even fit in a Dimension 3000.

[/quote]

You're absolutely right, Mr. Osprey, I am mistaken. I'm building two desktops and I got my notes mixed up. I apologize if I caused any major coronaries for the experts out here. I went back to www.crucial.com to verify my facts and I did indeed get specs mixed up. I installed the correct sticks of memory (1Gb 184-pin DIMM DDR PC2700), not what I initially stated. I'm wrong about that fact, too much happening and I mis-quoted the source. Oddly enough, since I figured I really screwed things up, I did another "ROOKIE" mistake. I decided that if I may have to re-install the OS, I should start off with the components being what I wanted. Probably stupid, but worse case scenario would be that I'd have to pay someone to fix it. In answer to "Fireberd", I've obviously found out this wasn't a minor upgrade. I should have done it in stages, taking my time with each level. But the damage was done.

Now for everyone's entertainment, here's the strange twist to EVERYTHING. I woke up this Saturday morning, and wrote all of this up to submit it to those who are smarter than I, and wait for better/cooler heads to prevail. Satisfied that I'm being diligent in my efforts to find a solution, I go about my business for the day.  Later in the afternoon, I figured reinstalling the OS was my last chance since I checked the forums and found no further assistance. I resigned myself to the fact I was going to lose everything in the hard drive, since I hadn't done a back-up for months. Before going through with this draconian action, my wife said "Why don't you just try it one more time before you start all over?" Not wanting to dismiss her suggestion, I agreed. I proceed to power up the machine and wait to see if I really had a lot of work to do. To my surprise, the computer Gods smiled upon me, and whatever was wrong yesterday was fine today. The desktop went through the whole start-up process without a hitch. It found all the new upgrades, installed all the drivers and got the parts to work as a whole. Upon the computer finishing what it wanted to do, I proceeded to verify all was well. I was able to get the wireless card to see the network and connect, the system saw the memory and the CPU change, and the whole system just seemed to be working great. I checked for problems in Device Manager, and found none. I scanned for hardware changes or warnings, but there were no yellow triangle with exclamation points to denote issues. I opened and closed the most difficult programs with ease. I did have to change the display settings to make it more comfortable for me, but no other issues could be found. I ran every check I could think of and did a virus check to be sure it wasn't a bug issue. My final test, was to log in and out of all the profiles multiple times and complete numerous reboots.. All tests were done without incident.

At this moment in time, the system is stable, the fan is purring like a kitten, internet access can be done wireless or via ethernet cable.  I can also run multiple applications without a strain on the system capability. I realize, that I really dodged a bullet and will be much more careful in the future. The only thing I have planned, is to remove the small original hard drives and replace it with a single massive capacity Hard drive. At that juncture, I will be upgrading the OS to Windows Vista Home Premium 64-bit. I cannot afford  to purchase the Windows 7 OS, and I really like the Vista OS for what I'm going to use it for. If you have any other suggestions, please post them, I will update condition over the next few weeks. The only other conclusion I can think happened, is maybe all the movement created an unstable environment for the hard drives or maybe something got jostled lose or wasn't connected correctly. I ran the XP repair and it found no issues or problems to fix. It seems very strange, but I've always been told to never look a gift horse in the mouth or spit in the eyes of the Fates. Looking forward to hearing from anyone with further insight or help with this situation. I'd love to hear any theories and reasons for the failure AND the miraculous rebirth of my first system rebuild/upgrade.

Have a great day, everyone.

Congratulations on your upgrade.  But just a couple of comments about your upgrade.  First the RAM.  You would want PC-3200 RAM, not PC-2700 with that 3.0 GHz CPU.  Now, the PC-2700 would work, but be slower.  And there is usually no cost difference.  On Dell Socket 478s, I like the Dell 9Y212 heat sink upgrade with the original mounting over the Intel.  The 9Y212 is recommended for 2.8 GHz Socket 478s and up.

If you are up to it, you could even put in a 4600 motherboard so that you could use SATA drives and an AGP graphics card.  ;-)  The 4600 is the same chipset and fits exactly in the same case.

David

David is correct. Because you upgraded to a processor that runs on an 800MHz FSB, you should have upgraded the RAM speed to PC-3200. However, because you have 2GB, probably more than necessary, you are not going to notice an improvement by swapping your RAM for the faster modules.

One more thing, the 3.0GHz supports hyperthreading, but this must be enabled in the BIOS. This will provide a noticeable improvement in performance.

By the way, my daughter's machine is a Dim 3000 and it is an exceptionally good machine, despite her best effort to mess it up with iTunes.

Well, I tried what you said about engaging the hyperthreading. I pressed F12 at start-up and enabled the hyperthreading, saved settings and exited out of System Setup. It started up and after I went into my profile, the OS installed the code/driver/processes needed for CPU hyperthreading  and after it did, it required restarting. I restarted the system and instantaneously the failure notice popped up stating that a recent hardware or software change has caused a cascade failure at boot-up. It gave me the option of trying all the ways to try and start it up. I tried them all, nothing worked. The computer now is a brick. I shut down completely, and waited a few minutes. I then started it back up again and pressed F12 to re-enter the system setup configuration mode. I reset the CPU back to having the hyperthreading disabled, since this is obviously the reason for the system cascade failure. I exited after saving the settings and tried to restart. Unfortunately, it's still not booting up. All I can think of is that maybe after being  shut down for a period of type, it will allow the the board to readjust/reset to the new settings of the CPU hyperthreading being disabled. I guess I should have learned from my mistakes, but I didn't know the reason for the failure, now I know what caused it. Hopefully the miracle of yesterday will duplicate itself in time and let me have my computer back. It is safe to say, that the engaging of the CPU hyperthreading caused the OS to rewrite things and create settings that aren't compatible with this Dimension 3000's setup or components. I should have left well enough alone.

That is a bummer about what happened during the change on HT.  When you pressed F2, did you go through all the settings to see what they said?  I would check all the settings to see that they make sense.

I would not expect there to be any need for the OS to install anything separate to support hyperthreading.  I don't really think that the hyperthreading was the cause of your system instability.

I assume that you used the proper heatsink compound on the 3.0 CPU when you were installing it.

The problem sounds more related to a hard drive.  I have gone years without any hard drive problems, and this last two months I have had four go out on different machines.  Luckily, I their Ghost backups were current and I was able to recover.  But it did surprise me after four years and 18 computers for friends and family and no hiccups.  But that Dimension 3000 drive may be nearing the end of its life.  If you have time for a replacement, I like the 250 GB ATA100 WD "AV" for $60 from newegg.  It has a very long MTBF and the price is fine for a PATA.  You could purchase a pair of them and some backup software and see if you can get your system back up.

Good luck.