VNC + VIRTUAL DESKTOP + JAVA ACCESS = WIN?

Ok, heres what I want to do:
I want users to be able to connect to my website and through some sort of client, use a sort of VNC on a "virtual computer" that doesnt actually exist. I'm pretty sure they can do this at Flinders University, so I know its not impossible.

If anyone can tell me how to do this, I shall reward thou with CP.

>>1
Back to [spoiler][b][i][o][u][s]ENTERPRISE[/s][/u][/o][/i][/b][/spoiler], please.