I have a XBox 360 for games and a Mac Mini for anything else...
I used to have a PC with XP up until about 6 months ago, but I simply grew tired of fixing it instead of actually using it.
Typical example: New game comes up, requires new DirectX 10.2 video card. Go buy Radeon/GeForce for $200, plug it in, power supply is not good enough. Go buy new power supply that's noisy as and you have to clean up every 6 months because it's a dust black hole. Finally computer turns on, have to go get new drivers, which in turn force you to reinstall DirectX. Make note to check for new video drivers every 6 months, because odds are next game is going to be incompatible with older drivers.
The Mini I have I paid $600 brand new, and I bought and installed 4 gig of ram myself for dirt cheap. I also added an external USB2 drive for cheap too.
I get to reuse my 26" monitor, Microsoft mouse, and keyboard of my choice.
I turn it on, and it works. The external drive doubles a backup volume, which is seamless with Time Machine.
I love it. I get done. The system doesn't get in my way. And that really is the bottom line. When I want to play games, I turn on the XBox and play.