BladePilot:
My old Dell with XP Pro sits next to the new system in my office and I normally have both running
Not sure if you have set this up but you may be interested in Synergy (
Synergy).
It is an opersource project that allows you to put the screens of two machines side by side and use a single keyboard/mouse to control both. As your mouse goes off the right of your left hand screen on 1 pc it picks up on the other pc's monitor to the right. You can even cut and paste between the two.
Its quite a simple master/slave (you can have multiple machines connected) environment to set up - if you do try it and are having problems let me know.
Cheers
Jof
p.s. I know it does not mention Vista on the front page but I have it working on Vista Ultimate fine.