Most would advise against disabling User Account Control (UAC) because of the added it security it offers.
It is reversible if you ever ned to turn it back on.
Here's how you do it:
Click "Start" > "All Programs" > "Control Panel" > "User Accounts" > "Turn User Account Control on or off"
Click Continue when prompted and uncheck the box called "Use User Account Control (UAC) to help protect your computer", and then reboot your PC.
When you PC has restarted the UAC should no longer nag you.