Vista requires a lot of resources and a lot of patience. Once you get it working exactly how you want it, it's smooth sailing from there. I would give this to newer users since it uses Least Privileged User which protects most stupid people. The only problem is that it is over-zealous.
Windows 7 is a harmony balance between XP and Vista taking the good from both. The new taskbar is an absolute must. You'll never know how you got around without it.
[Edited by L, 11/10/2009 10:14:16 PM]