It depends what kind of experience you are looking for. The XBox 360 was designed for the sole purpose of games, and has beautiful graphics quality. The online play is very good, too.

If you don't have a 360, but have a PC, you might not want to get a 360. Your graphics won't be as nice, but at least you can upgrade each part of a PC individually, a feature the 360 does not have. One problem with the PC, though, is the gaming library. There tend to be more games for consoles than PCs.