I meant to post this some time back but never got around to it, but anyway, here goes...
For the longest time I had a shitty PC gamepad that was actually worse than using a keyboard for emulation and such. I could have picked up a nicer one of course, but I never had the extra money or the desire to actually buy another. A couples months back I stumbled across a program called GlovePIE, (originally created for use with a virtual-reality glove, hence the name). Over time it has added the functionality for almost any sort of computer input device to be used as a game controller, (even MIDI keyboards), and this includes the controllers for the 360, PS3, and Wii, (with or without the Classic Controller). With the Wiimote or Sixaxis you can even assign the accelerometer axises to emulate those of a mouse or other keys, (very cool with flight-based games).
Anyway, it's free, easy to use, and it's worked fantastic for me, (I'm using it with my PS3 controller). Keep in mind that if you're using a Wiimote with the program your computer needs to have bluetooth. You can download, read about, and get instructions on how to use the program here:
http://carl.kenner.googlepages.com/glovepie_downloadThoughts?