Definitely turn off UAC!
It's just nannyware. Microsoft seems to think nobody knows how to use their computers. largely they're right, but after installing Vista, the first thing you should be presented with is an option to turn on UAC:
Windows wants to protect you from your own idiocy now. Turn on UAC? Checking the No box will completely disable all nannyware on your computer, and you will die soon.
Are you sure?
Are you sure you're sure?
Are you really really sure?
UAC is disabled. Don't say you weren't warned. Good luck.

It's funny, because in may ways Vista is designed for professionals who have a need for loads of memory, better graphics, quicker speeds, particularly 64 bit Vista ultimate, but its initial default setup is nothing more than a severe hindrance for those who want to just get going, and you may be changing settings for a couple weeks before you have it right.
I wish it just had a checkbox for "Leave me the **** alone and just be an Operating System - I don't need a babysitter"