x-win32
http://www.starnet.com/
Got fork out the cash for it though ($60 US for students). My school has it on their Windows boxes, and it works pretty well. You can also use SSH with X forwarding. In your /etc/ssh/sshd_config file you'll need to change the X11Forwarding to "yes". When connecting via ssh, use the ssh -X -C -l username host
the -X is for X forwarding, and -C compresses the data.
^^ As above, be more specific in your "Subject". If your specific, you'll get more people who can actually help you.