The directory access should set the user to be ASPNET if on Windows 2000/XP or NETWORK SERVICE if on Windows 2K3/Vista. Which are you using? Admin may work for you on the local machine, but won't work for anyone else.
Mitchel Sellers keeps a very good and updated collection of installation instructions at
http://www.mitchelsellers.com/blogs.../294.aspx. You might want to compare his instructions with what you did.