Over the years I've built PC's but I've also owned four Dells. One of them was a Pentium 3 that I kept on my desk until last year when I finally unplugged it because I no longer needed it to test programs for Win98 compatibility. It was eight years old and still ran fine. I never replaced anything in it except the CD drive. On my network now I've got two P4 Dells which have run nearly 24/7 for four and five years respectively. Between the two of them, nothing has ever broken except a CD drive.

I think Dells are fine if what you want is exactly the original equipment you get in them. The only problems I've ever had with them is when I wanted to add stuff later. For example, the power supplies tend to be pretty small. Big enough for the original components, but not much more than that.

As for the cost of a Dell vs. rolling your own, I haven't compared lately. But over the years there have been times when I compared and buying from Dell was cheaper.