Can't you use the windows program "connect to external desktop" (roughly translated from Dutch)? I use this to connect to my XP machine from my Vista laptop and it works great. There is also a programm to allow loggin in on the XP machine while an other user can keep on working on the XP machine.
Use www.crossloop.com.... interacts simpler than "Remote desktop" with any version of Windows.
Use an ID no to be passed on to the "guest" on a shared session.. no other adjustment necessary.
Both parties can interact independently.