Does the PC have a good video card? You can always buy an Xbox 360 controller for it. They are the official controller for the Games for Windows platform. Mass Effect, Grand Theft Auto 4, Mirror's Edge, Bioshock, Fallout 3, Street Fighter IV, Burnout Paradise, Assassin's Creed, Prince of Persia. A ton, maybe most, of the top games for PS3 and Xbox 360 are released for the PC. And of course all the FPS games actually play better thanks to the keyboard/mouse combo. Hell, you've even got your own exclusives with the likes of World of Warcraft and Crysis and Total War.
So, yeah, why go to all the hastle? If you want to play games, pick up an Xbox 360 controller (make sure you get the one that comes with the wireless PC receiver) and get playing. Unless you specifically MUST have Metal Gear Solid or Little Big Planet, the PS3 isn't really going to give you anything you don't already have.