I'd first like to say that I think Channel9 is a great idea and I'm excited about seeing how it evolves over the next year or so.
Do I run as admin on my computer? No, I don't. I have WindowsXP Pro and I have two user accounts: an admin account which I use sparingly, and a limited user account I use for day to day stuff. When I need to do something requiring admin rights, I simply open an IE instance with my admin account using Run As...
Using Run As... seems to suit all my needs with maybe one or two rare exceptions. I can defrag, edit the registry, and configure security policies just to name a few.