This guy wants me to trade my Vita for a DS Lite and GBA with 18 games between the two. I don't think it's worth it...
if you really had to think about that you don't deserve the vita
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.