Quite frankly, all these folks talking about "Dell is evil hurr prebuilt evil derp" do not know what they are talking about. Yes, you CAN get a pre-built with better bang for your buck (although that's hard to do anymore. Pre-built prices are pretty damn good now-a-days), but people forget that walking that path is not for everyone.
I work part-time in IT at an office, and we use Dell computers. It's my job to make sure all of the electronics are working properly (among other things). Actual issues with PC hardware is less than 0.5% of my time spent there. We have no issues that aren't just general wear-and-tear.
(i've been replacing parts and building PCs for the better part of the decade, so I've seen it all)