Hi guys, can anyone help? This script would have to work on both XP and Vista

Here's what i'd like:

Basically I only want to call another script if UAC is OFF - otherwise the install fails and never works again:

Code:
Check if running Vista - if so then check if UAC is on or off.

If on, end script

If off, call other script (which I already have - it's a .bat file to install sophos)
Thanks