Dell has always been been pretty good in my book. I have bought computers for them for myself, my family, and friends for a long time. So far I've bought well over 200 computers and out of those, I've had problems with just 5!!
Out of those 5 that had problems:
-1 desktop had the capacitors bust after about 7 years.
-1 was a laptop that overheated but I'm pretty sure it was due to a lightning strike which blew out my plasma TV as well?
-3 desktops were bad out of the box and were all the exact same model and specification so I simply switched out the model and problem solved after the return.
I view Dell as disposable computers that last usually to the 5 year mark without too many problems. At 5 years it's better just to get a new computer anyway because of technology even if you built your own. If something goes wrong, the warranty just gives you a new part and your back in business. For the price and value you can't beat them.