Can't speak for others, but I have not had any of the problems.  I received my system on 2-29-12.  I did have to tuck away a cord that was interfering with GPU fan when I first received it.

No overheating, wifi works great (<100 ping on WoW at all times, usually <60, and that is several rooms away from the router),  and no problems with DVD.

I am pushing Skyrim on max settings with HD textures via HDMI to the living room TV, no sweat..

I received mine on 3/6/12.  I had no issues, but the first thing I did before even plugging it in was taking the cover off.  After that, I unloosened the one screw holding the DVD drive down and tightened it just enough to hold it snugly.  I then took out the video card and replaced the Hard Drive with a SSD.  I then made sure the video card was seated properly and tucked the cords away.  I didn't do anything with the WiFi except install the drivers when it was time to do so.  The thing boots in about 10 seconds :)  and runs great.

Received mine on 3/9. Runs fine under normal operations, but as soon as the GPU starts getting used the system shutdowns down. Checked the cables, reinstalled drivers, etc. I will be calling Dell to return it. Wifi and optical drive are fine though. 

I want to order the X51 but I need it to work properly out of the box.  I'm not one to open the case and make adjustments.  I like the X51 the way it is configured.  I need to order via Best Buy because I need to use gift cards.  I'm concerned the Best Buy units are pre-built and warehoused so I dont know how long to wait to order to get a unit that has had all the issues resolved.  I really thought the Alienware was a premium brand that avoided having so many potential issues out of the box.  I may just end up with an XPS 8300.  Not as convenient size but a little more bang for the buck and hopefully not as many potential issues.  But I really like the X51.

Mine arrived 3/9. perfect out of the box. The optical drive problem has been fixed. anything shipping from 3/4 has the new bezel. Plug and play!

Hi Apex26, have you tried this? http://dell.to/xqwPfK

Yes I did try that. I have a technician coming out to replace the graphics card.

Video card was replaced and the system is working fine now.

Any updates from Dell on the CPU fan noise and Wifi issues ? .. am still looking at the X51 but these issues in particular are putting me off greatly as they are still under investigation it would seem.