If you keep UAC enabled, the only difference between a standard user account
and an administrator account on a home PC is when a program needs
administrator permission.
With an administrator account, a window will pop up asking you for
permission to run. You will click Continue, and that program will be given
the admin permissions that your account allows.
With a standard user account, the window that pops up will ask for the
username and password of an administrator, and then the program will get
whatever admin permissions that admin account allows.
- JB
Vista FAQ
http://www.jimmah.com/vista/