Canon have a fantastic little app, which works on both Windows and Mac, called EOS Utility, which among other things allows you to do time lapse photography!
I lost my CD ages ago, because you know … everyone knows that all responsible companies let you download support tools from their website ..
Unfortunately no one informed Canon of this amazing new way of thinking, and they only let you download an update for the EOS Utility application, which throws a massive hissy fit if you try to install it on a machine that doesn’t already have it installed!