The problem with PCs is that the components vary from machine to machine. If you know what you are doing, you can avoid many of the pitfalls of mixing and matching. My pc's are rock solid, I wouldn't trade them in for a Mac. But I'm a PC game enthusiast and the Mac's library of games is laughable. I use both a WinXP box and a Linux box at work.
I'm assuming people actually mean "Windows machines" when they say PCs, because as we all know, Macs are PCs, unless you are using some kind of Mac Mainframe ....
V