We have had more trouble with Gateway PCs than anything else. Mine is down, again, for the seventh time in three years - a complete crash, and Gateway could never seem to figure out the problem. And customer support is horrendous.
Our Dell PCs have been servicable. The Dell laptops, OK, though we've had a couple crashes. Customer support has been OK, though a lot is in India, so they're hard to understand.
Our next PC, though, is being built from scratch. I highly recommend it if you can live without customer support! It's more than $1000 cheaper than a comparable Dell or Gateway system with all the bell and whistles. (Don't ask me WHY we need these bells and whistles - our roommmate is a very bad influence.)