Nice score dude! It's a really cool experience picking things up for free! I recently acquired 2x of the first aluminum 2007 iMac core 2 duos (2ghz, 4gb ram) from a friend who had them destined for recycling in a basement. I was quite happy to say the least. Clean installs of snow leopard on both machines, everything running perfectly and remarkably quick for machines that are 5-6 years old. One iMac was suffering from the ati 2400 gt problem that was easily fixed with the kext file replacement remedy. I will take one machine right up to mountain lion and get a magic track pad, the other will stay on snow and be loved by my girlfriend who will use it for internet browsing, copy editing and music. I'll post up a couple pics soon.

Enjoy your machine! The white ones are really a timeless design. The aluminum ones are cool, but everything apple is aluminum these days.