Put simply graphical performance means next to nothing now, all games can look stunning and should look stunning. The 360 has the biggest library of games right now and if you're wanting variety then it's the console of choice, but if you're an avid MGS or GT fan then get a PS3, the best franchises are available on Playsation. Oh and as for Halo 3, underwhelming at best, as is Mass Effect.
The other point about the PS3 is that you'll be buying a Blu-ray player that can play PS3 games, given that the PS3 is cheaper than a blu-ray disc player, I believe.
Saint Del is considered a holy healer of diseases of children, but also as a protector of cattle.