Been messing around with emulators on the Xbox. It's not like I've had it since last year or anything. Very impressed so far, I knew it was meant to be fantastic for emulation but I didn't think it would be quite as good as it is. Looks like I can safely pack away the NES, SNES and Genesis now and save some space.
That's OK, that giant paperweight will take up ALL of those consoles space up good & proper
THE BEST METHOD to run PSX games (and everything else for that matter) is via Retroarch - http://buildbot.libretro.com/nightly/
If you have any questions on how to set it up on Windows please feel free to ask, its very easy.