At work I'll change my user profile when needed. In times when I don't need much admin rights, I'll go down to Power User. But at the moment I'm running admin cause I need to test some new tools and play around with some services.
At home I'm just a user and it works out great for me ... but I share that computer with my girlfriend and she keeps nagging about the freedom she had in Win98/Me. She sometimes gets mad about it and thinks I don't trust her.