UAC in windows vista are lets be honest a pain in the neck if you are developer when you first start using Vista you seem to spend you first three weeks fighting them as you re-install stuff and start the programs. Most developers shout scream then switch off UAC. The biggest problem and what Ian G says in excellent post . http://www.interact-sw.co.uk/iangblog/2007/05/09/uacproblem is that Windows developers are one of the root causes that lead to security problems on windows. It took me a month after I switched off UAC to switch it back on. I did not switch it on because I wanted it back on or for the security reasons. I switched it back on because most people I know as users don't know how to switch off UAC controls they never get there, I decided I was potentially writing software that was not going to work as expected on standard vista install. For developers the cost and pain of developing software that requires a double test environment is a nightmare and one that I decided was not acceptable. The only problem I now have is I find myself on Windows XP machines right clicking and looking for Run as Administrator for Visual Studio. If you are windows developer for vista not having UAC is not only a bad decision because of security reason but you are also potentially doubling your test environments.