YOU CAN USE VIRTUALLY ANY CONTROLLER ON A PC NOWADAYS, HOLY SHIT.
Hell, the stores near me sell USB mock-NES and SNES controllers, and are always stocked with PS2 controller converters.
I'm pretty satisfied with just using my PSP as my emulation machine, can even hook it up to the TV for a bigger picture if I feel like it. I use MAME OSX for whatever isn't supported on the PSP.