I've used and programmed computers for many years. I play some games (like Company of Heroes) on PC but I play most first person shooter games on a PlayStation. Although I like my iPhone and laptops I still think desktops are the the best. If I really want to surf the web, play games, etc., I want my 24" screen and a comfy chair.
I haven't build my own PC (yet) but the research has been fun so far. I like thinking about all the trade-offs and comparisons of various components.