ElDiabloConCaca said:Simple: VNC.
Use this server on your Mac:
http://www.versiontracker.com/dyn/moreinfo/macosx/16699
Then, use whichever your preferred VNC client is on the Windows machine. If you haven't used VNC before, take a look around http://www.versiontracker.com on the Windows software section for a decent VNC client.