You cant just connect the PS3 Controller and start playing games, you need to install a driver and a program, this tells you how to do it.
http://www.hardcoreware.net/how-to-playstation-3-controller-64-bit-windows-7-vista/
never tried it myself though, but Keyboard and Mouse does me, i like that better than controllers.
yeah, hash!
**** ye ... i just connect the joypad and windows 7 ultimate finds the drivers automatically. Invest in a good os
win95 just aint gonna cut it