Is Windows7 UAC really necessary with NIS 2010?

I am new to Windows 7, having switched from XP about a month ago.  I am finding UAC (User Account Control) a major pain, it interferes with a lot of my software.  I have Norton Internet Security 2010, which is pretty rigorous in identifying possible risks to my system and asking me if I want a particular file to execute.  UAC seems designed for the same purpose, but it is far too aggressive for my purposes.  As long as I have NIS 2010 up and running, is there really any significant risk to my system if I just disable UAC (set it to the "Never" setting at the bottom of the slider)?