If you want to work with the same installation, you should seriously consider the Remote Desktop Server/Client solution, bundled into every windows OS from XP. Basically, this app displays the view from your remote desktop to your local one, using highly compressed images; this works even via low-bandwidth internet connections
While the XP version can only handle one user simultaneously, the one in Windows Server 2003 (and in Windows Server 2008, I presume) can handle multiple users (up to a certain limit).
Disadvantages, and side-effects include:
- virtual pc via RDC is slow
- anything using the 3d acceleration will be slow (at least using XP/2003)
