360 depends on what functionality you want. You can buy the wireless 360 controller for PC - or possibly find the receiver alone for a little less and use a 360 controller you already own. All you need to do with that, assuming you want to use it for officially supported functions, like games that specifically support the 360 controller, is plug in the receiver and sync the controller. 7 already has the driver support built-in.
Things that don't have that support will recognize the triggers as extra axis n' stuff (not buttons), which may not be what you want. At that point you need to run 3rd party drivers. I'm not sure how the little keyboard is handled as I don't have one.
PS3 controllers are possible to get working, but the drivers are kind of hacked together. -Wired- ones, however, seem to work perfectly fine, but I think those tend to be limited to specialty controllers like arcade sticks for fighters. I picked up one of the PS3 SF4 sticks for cheap on Black Friday, and it worked right off the bat, no extra software required - but that's wired USB.
IMO, if you want a wireless Dual-Shock style controller, it'd be much simpler to just buy a similar design that's made for the PC.
IMO, you may want to look at something other than gamepads if your goal is more for media PC use. Might look into a Media Center remote, as those can be found relatively cheap - or just look for a micro-keyboard with an integrated trackball or something, such as
this one, depending on what your intended use is.