Through the use of emulators, it is possible to play virtually any Mario game on your computer. All one needs is a emulator and a ROM image of the game. Of course, distributing copyrighted games is illegal, so please do not ask us to send you ROMs.
If you want to know more about emulation, check out ClassicGaming's Newbie Guide.
If you need emulators, check out Patent Pending.
For .SPCs, see the SPC page.