I don't know caperjack, seems like an unfair test, considering the fact that UAC is NOT an anti-virus or a malware protection program.
It is however, just what it's title says "USER" Account Control", which from my understanding, protects your files and settings from other users on that particular PC.
Maybe I missed something here.

Don

yeah,first im still learning all the special features of win7,[never using vista im new to all of them] but i guess its because of the hype of uac,part of uas is the popup you get for upper admin clearance to allow a program to run,like i said im still learning and time is scarce these days

check the first paragraph as to there definition of uac and it seems its meant to do a lot more that just security between users .http://en.wikipedia.org/wiki/User_Account_Control

The UAC default is all wrong in Windows 7, much safer to allow nothing even if it does add more hassle for the user. That said, the Sophos testing was rather misleading I think. I wrote about it here and my conclusion was that I'd like to see the same test on a Windows 7 machine running some AV, which would surely be more valid - especially as the viruses that were thrown at the machine in the labs were brand new samples fresh into the lab. I'd like to see how other versions of Windows dealt with them, I would suspect exactly the same to be fair.

UAC does more than just prompt. Its behind IE's protected mode and needs-only elevation. That means that e.g IE will be sandboxed and run under the lowest privileged user account rights, and e.g apps will only be installed elevated if they request it.