In Windows Vista whenever you try to run any software or any other executable file, a dialog window comes in front of your screen and asks your permission. For most users, the response is always to continue.
If you are an advance user and feels that you don’t want this window to come and ask your permission whenever you do something then this post will guide you; how you can turn off or on, the User Account Control.
In Control Panel, go to User Accounts, click on Turn User Account Control on or off.
Un check the option and Click OK. You can always turn it on again from here.
However it is recommended to keep UAC enabled, to protect your computer against viruses and other malicious software.