I have had a few problems with mine. Sound dying (fixed with new motherboard), fan 1 squealing.
Parts replaced: (times)
fan 1 (1)
fan 2 (2) second time was my fault
LCD hinge cover (power button etc.) (1)
All in all I am very happy with the dell service, I have gotten my $$$ worth out of it already and I have only had it for about 7 months. The only gripe I have is that when the dell tech replaced my motherboard, he forgot to put the cmos battery on the new mobo. so I was without a cmos battery for about a week. What I have found is if you chat with the techs through the dell website (the live chat stuff) if you tell them exactly what you need, and that you know what you are talking about and that you know how to replace it, then they almost always send it out asap.