The discs that come with your GPS don't work on MACs.

Garmin's been working on MAC programs for a while, and the only thing they've come up with is Bobcat, which is ok. You can get it here:

http://www8.garmin.com/support/downl...ls.jsp?id=3886

Your best bet is to install Windows on your MAC (if you've got the Intel chip) and run your GPS through Windows.

Or, do like I did and be really nice to your girlfriend (who runs Windows) and install it on her computer.