I will never turn off the UAC after a certain event that happened back in November. I was visiting a site that had quite a few ads for the first time. Suddenly the UAC thing popped up asking if I wanted a program to be able to make changes to my computer. I can't remember the name of the program, but I had never seen it before. I clicked no, closed Chrome, updated then ran MSE and it found a virus and promptly removed it. I'm not sure if MSE would have nipped it in the butt before it did what ever it was designed to do if it wasn't for the UAC stopping it. It slows me down, but it has it's place. I can't blame MS for trying and at least I don't have to put in my password constantly like in Ubuntu and Knoppix.
Not saying UAC will help even half the time, but it helping once is good enough reason for me to waste two seconds every once in a while. It's better than wasting two hours removing a virus or reinstalling Windows.