If it's under warranty, by all means have Dell replace the fan.  There are only two CPU  upgrades you can use - the T7400 and T7600.  Neither is much of a boost, and upgrading the CPU will void your warranty (no, Dell won't warrant or do a CPU upgrade).

I have the T7200 at the moment but just wondered if any faster one would make much difference, from your answer EJN63 it sounds like difference will be small so not worth upgrading, I know there is a limited range available for that mainboard chipset as I also have a Lattitude D830 same speed but CPU is T7300 (2.0GHz 4MB cache) but that is newer chipset at 800MHz on newer mainboard. Reason I was considering changing fan myself is that years back i had 2 Inspiron 8000 notebooks and the mainboard on one went and they were covered by NBD onsite but they wanted to collect and return which I refused as I had paid for NBD onsite and wanted that cover, they messed about but the sent an engineer, he was in and out within 30 mins. job done, the other case was a dodgy keyboard on one, they turned up 3 days after they were booked to come and I was away so he rang me and I said to leave keyboard for me to fit, in the end they did, not very good for NBD service, being ill a lot at very short notice of attack I have been delaying it because of that experience. I have stripped and rebuilt the i8000 a couple of times it was easy so don't think this would be much harder, I notice on forums several have done it to clean out and improve cooling, the fans are fine at this moment but just my luck to collapse when warranty runs out. Thanks for your help guys.

The T7200 is so close to the maximum speed of Socket M (topping out at T7600) that  it's unlikely an upgrade CPU will make much, if any perceptible difference.  The T7300 (and all the other T7x00 with x = odd or above 6) CPU is Socket P - physically the same but electrically incompatible with the older Socket M systems.

Replacement of the fan is up to you - though remember if anything is damaged in your repair, it won't be covered by warranty.

You can even call and see if they'll send you the fan and allow you to replace it yourself - sometimes they will do that, even with internal components other than RAM or the hard drive.

Thanks, I have decided not to bother trying to upgrade CPU as it seems from you all it's not realy worth doing. I phoned Dell today and they have after a lot of pushing agreed to replace fans, heatsinks & a faulty keyboard (one key cap keeps coming koose) but can't say when as they don't know the spares situation, they pushed for me to allow them to collect and return but I refused as I paid for 3 year NBD International Warranty so after half an hour and 3 checks with supervisor he had to call me back to confirm an engineer will be sent to do the work, now I have to wait hoping the engineer calls me as requeted before turning up. I don't think they should be allowed to sell NBD warranty if they can't honor it.

Will report back when I get a result.

Got a call from Dell just before 9am to say engineer will call me to do repairs today, engineer called 10.30am to say calling between 2pm and 4pm, a polite young man arrived about 2.30pm and left by 3.30pm. Changed keyboard, CPU heatsink + fan & graphics card fan, quite an easy job once you have watched them do it, only comlaint I would have expected him to have to have had a can of air to blow dust out or a vac to suck it out but just took out filthy fans and heat sink then fitted new ones with all the filth left in machine so I think i will have to open it up to clear out the muck before it gets into the new fans and heatsink. Feel a lot happier now it's done and next day, it's first time they have managed that for the 10 years and 4 systems I have bought off them.