Readers of this site and listeners of the Windows Weekly podcast know that I advocate the use of User Account Control (UAC), Microsoft's unfairly maligned security technology. UAC does a lot more than just prompt you when you're about to make a potentially dangerous change to the system or run a program you downloaded from the Internet. It's also behind such related features as Internet Explorer 7's Protected Mode and Vista's virtualized file system and registry. So running UAC is, I think, a necessity for all Vista users.
That said, I do understand that some people find UAC's regular prompts to be somewhat annoying. Fortunately, you can leave UAC enabled but turn off the prompts. The following tip refers to Windows Vista users utilizing an administrator-class account (which I assume is most people) and should be utilized by power users and others who really know what they're doing.
Windows Vista Business, Enterprise, and Ultimate
Open Local Group Policy Editor (Start Menu Search, gpedit.msc), and navigate to Computer Configuration, Windows Settings, Security Settings, Local Policies, Security Options. In the right pane, scroll down to User Account Control: Behavior of the elevation prompt for administrators in Admin Approval Mode. Double-click this entry and use the drop-down box in the Local Security Setting to change the value from Prompt for consent to Elevate without prompting. Then click OK and chose the Local Group Policy Editor. (Users looking for even more stringent security controls can go in the opposite direction and change the value to Prompt for credentials. This will cause every UAC dialog that appears to require you to enter your password.)
Windows Vista Home Basic and Home Premium
Open the Registry Editor (Start Menu Search, regedit.exe) and navigate to HKEY_LOCAL_MACHINE, SOFTWARE, Microsoft, Windows, CurrentVersion, Policies, System. In the right pane, find the value named ConsentPromptBehaviorAdmin. Double-click it and change its value data from 2 to 0. Then click OK and close the Registry Editor.
Like other UAC changes, this change will trigger a Windows Security Center warning. To turn off this warning--not recommended unless you really know what you're doing--launch Security Center and click the link titled Change the way Security Center alerts me in the left side of the window. Then, choose Don't notify me and don't display the icon (not recommended) from the resulting dialog.
This tip is derived from Chapter 9 of Windows Vista Secrets 2nd Edition, coming soon from Wiley & Sons.