Sp-s are for those who don't know how to use a pc (or do not want to bitch around with config....)
The only games that i play for sp are Crash(the fox/wolf thing),NFS,WWF/E
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The only other good thing about ps-s is the joystick.
You can play 2x2 wwf smack down.
But you can not find a good enough keyboard to play 4 pople at the same time
also sp joysticks are cheeper(at least here they are) than pc