My last three are/were homemade jobs, prior to that had an old compaq someone sold me for 20 dollars. I upgraded the heck out of what I could, but there's only so much you can do to those things.
Current machine is a P4 2.4Ghz with 512mb and an nVidia 64MB card, bunch of other stuff, blah blah spent under 500. I'm incredibly pleased, except the power supply I bought died after 2 months. It was teh lame, I guess. I just went and got an old one from another machine, and everything's fine again.
I won't buy pre-built from Dell because I know where they send you when you call in for Hardware support or replacement. India, Pakistan, or the Phillipines. Or Manila.
I do software support for them until midnight Friday night/Saturday morning. I'm done after that, different job, more money.
Technically, I have a week of vacation next week, but I'll be working at the new place all week too.
But if someone knows jack about PCs, and they want to get a machine that runs e-mail and "tha intraweb," a $450 Dell is tough to argue with.