http://www.trackmanianations.com/Free. so very.
Its a 265~ meg download, windows only
But its a fun game. if you like TT'ing with loops and boosts and all that jazz. There's also the option to play online. sadly, just like MKDS, there's no collision detection inbetween players.

As long you keep the settings on the very minimum, i think you don't need a very beefy computer to play. I dunno.
Edit:

On lowest settings i could acheive on this computer.
This post has been edited by Elly on Mar 17 2006, 08:38 PM