From PC to Mac, you can set up VNC with using a VNC viewer on the PC and the updated Remote Desktop part on the Mac (will need to download the latest manually from Apple). From Mac to PC (XP Pro only) you can use MS Remote Desktop that you can get from their website. You could also setup a VNC server on the PC and use a VNC viewer on the Mac. A good VNC viewer on the Mac is "Chicken of the VNC". http://www.versiontracker.com and look up VNC.