Play Super Mario Bros on your computer -- Follow these instructions and you'll be playing Super Mario Bros on your PC in no time!

First you'll need a NES emulator:
JNES is a great Nintendo emulator: http://www.wiilovemario.com/download/emulator/jnes_0_6.exe

Next you'll need the Super Mario Bros ROM. We DO NOT host any roms here... but you can find them littered all around the 'Net. Use the following Google search string to find what you're looking for:

This is for finding SNES (Super Nintendo Entertainment System) roms
{-inurl:(htm|html|php) intitle:"index of" +"last modified" +"parent directory" +description +size +(smc|rom) "mario"}

This is for finding NES (Nintendo Entertainment System) roms
{-inurl:(htm|html|php) intitle:"index of" +"last modified" +"parent directory" +description +size +(nes|rom) "mario"}

This will bring up a bunch of sites that have NES ROMs and other goodies. You can also use the above search string to find other stuff by replacing "mario" with whatever ROM you're looking for. Have fun!