Turn Off Only Part of UAC
A more granular approach to UAC is available too. Though the User Accounts Control Panel limits you to turning UAC on or off, you can do a bit of fine-tuning via the Group Policy Object Editor. Click Start, type gpedit.msc, and press Enter. Confirm that decision when UAC prompts you to do so. In the tree pane on the left, navigate to Local Computer Policy\Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options. With Security Options selected in the left pane, scroll down the right pane to the User Account Control options.
These settings are anything but clear, but you can do a couple of useful things with them. For example, if you don't mind receiving UAC prompts for most tasks but you want to be able to install software without any UAC nagging, double-click User Account Control: Detect application installations and prompt for elevation. Select Disabled and click OK. Restart your computer to see the change.
Another possibility is to leave UAC turned on but set it to knock off the prompts. Unlike turning off UAC altogether, suppressing prompts preserves the "protected mode" security feature of Internet Explorer that UAC confers. Of course, turning off the prompts is considerably riskier than retaining the default settings, but it's better than disabling the entire applet. To take this approach, double-click User Account Control: Behavior of the elevation prompt for administrators in Admin Approval Mode. Choose Elevate without prompting from the dropdown list, and click OK (see the image below). A pop-up will complain that UAC is not on, but you can ignore it.
Fine-tune your User Account Control interactions by adjusting settings in the Group Policy Object Editor to suppress the prompts that User Account Control wants to pepper you with. The resulting "protected mode" isn't as safe as leaving the default UAC settings in place, but it's a lot more peaceful.
Vista Home Premium doesn't have the Group Policy Editor. To make the change in that version, you must edit the Registry. Before attempting any Registry changes, back it up following the instructions in "Block Spying Cookies, but Keep the Helpful Ones" (scroll down to the blue text box near the bottom of the page). With your Registry backup in place, click Start, type regedit, and press Enter. In the tree pane on the left, navigate to HKEY_LOCAL_MACHINE\SOFTWARE\ Microsoft\Windows\CurrentVersion\Policies\System. With the System icon selected in the left pane, double-click ConsentPromptBehaviorAdmin in the right pane. Change the Value data to 0 and click OK. You should see the effect immediately (no restart required).