The User Account Control security feature was one of the most reviled additions to Windows Vista, with good reason -- its constant warning messages asking for permission to continue many operations drove users around the bend. UAC has been significantly improved in Windows 7 so that it's not as intrusive as in Vista, but you can still tweak it if you like.
Here's how to turn UAC on or off, and make it less or more intrusive than the default:
1. Go to the Control Panel --> User Accounts and Family Safety.
2. Click User Accounts, then click Change User Account Control settings.
3. From the screen that appears, use the slider to select the level of protection you want. Here are the four levels and what they mean:
Always notify me. Think of this as UAC Classic. It works like Vista's UAC: When you make changes to your system, when software is installed or when a program tries to make a change to your system, an annoying prompt appears.
Default -- Notify me only when programs try to make changes to my computer. This is, obviously, the default; make a change yourself and UAC leaves you alone. When a program makes a change, a prompt appears and your desktop goes dark, just like it does in Vista. Otherwise, UAC sits there silently.
Notify me only when programs try to make changes to my computer (do not dim my desktop). This setting is identical to the default setting, with one difference: It won't dim your desktop so that you only see the UAC prompt asking you to take action. This presents a slightly elevated security risk over the default setting, because theoretically a program could allow a malicious program to interfere with the UAC prompt.
Never notify me when: In this one, UAC is completely turned off. This is, of course, an insecure option and not recommended for most users.
After you make the selection, click OK. Depending on the selection you made, you may need to restart your system for it to take effect.