Enable Power Users group in Vista?

Hello,

I work for a large university and we are about to deploy an AD file server
that has about 10 Windows Vista Ultimate machines on it mixed with some XP
machines. I would like to be able to use the Power Users group in Windows
Vista so that I don't have to give standard users an administrator password
or babysit them every time they want to install a program. This works great
on the XP machines, of course, but not in Vista. All of the documentation
I've read on the Microsoft site says that I should be able to enable the
Power Users group in Vista to get it to work just like XP, but it doesn't
tell me how. I've called Microsoft, and the tech said that if he told me how
to do this, he would be overstepping his scope and could get fired. That's
when he suggested that I ask you guys. Any ideas?

Thanks!

-Clayton