I've had a few people send me e-mail asking, "What is the password for ADVENTUREWORKS.LOCAL\darren?"
His password is Pass@word1 and it was provided on the VPC download page. For those who obtained the VPC at Microsoft from an itnernal share, I don't think this information was provided.
Also, see Omar Villareals' blog post from TechEd [Things you should know about the Team System Virtual PC DVD handed at TechEd.] for some other handy information, such as how to get Live Communication Server to work.