It has OS X Lion installed, the latest version it can run, which is very outdated. Download your only run the installation steps. Open the Boot Camp Assistant application. Note, If you are using one of the Macs listed below, you should download Boot Camp Support Software instead. It already had rEFIt on it, I just connected a Windows 7 boot thumb drive, and away I went.
We installed Boot Camp on the iMac Core Duo, the software will also work with the Mac Mini and the MacBook we could run the app, we first had to update our iMac to Mac OS X 10.4.6. While virtualization apps like Parallels or Fusion allow for installing just about any.
