using a Playstation controller with Vista

[Marlow]

I've borrowed a PS controller from a friend and am using a USB adapter to work with my computer. I'm not using it for poker, but for a videogame (please let me know if posting here is inappropriate - if so, I apologize).

For some reason, the controller has limited functionality. I assume that the driver needs to be installed, but I'm not sure. Also, I really have no idea where to go to get the driver. I downloaded one, but Vista thought it looked shady, and I had to agree, so I didn't install it.

Where should I go for a clean driver? Do you think a driver is what I need in the first place?