I have to say PC cause if you build your own computer it probably will only cost $400 for a decent one and you get a ton more besides gaming. Plus is runs pretty well when you play games. At least better than consoles.
PC is great for hardcore games - it really is the epitome of hardcore systems, with the ability to have graphics to rival the ps3 and xbox360 put together, speed to match them both, and so many modifications it'll make your eyes spin. Basically, if you're a hardcore gamer, you're a PC.
However, it does cost quite a bit to make and maintain, not to mention that lugging around a great big freaking computer does make it uncomfortable.
For localized multiplayer games, I'd choose the ps3 over the PC - LAN is great and all, but nothing really matches sitting with a controller in your hand drinking Pepsi and kicking ass.
