I think some people are forgetting the fact that everyone has a pc. A lot of people don't realize how many games they're able to play on a pc or maybe they just choose not to. Either way that option is still available. Ps3 games like God of War or Uncharted won't ever be coming to xbox and probably wont' be on pc for the near future- the only way to play those games is on that system.
Boo hoo left 4 dead isn't on ps3 - so i bought it on steam instead. Crisis averted -_- And I didn't even have to upgrade my computer for that game.