I have installed Visual Studio 2008 and am running it as a non-Administrator user.
I have a Web Application project I am developing and would like to debug it using
I've never tried this, but it might be worth a shot.
While logged in as an administrator, you could change the identity under which the service and/or the application pools run. Make them run under the same non-administrator account you normally use. Then when Visual Studio attempts to attach to the process, the security context will match between the debugger and the process being debugged.
I think you'd only need to change the identity under which your application pool runs.
Here's some more detail from James Kovacs' Weblog: Debugging as a Non-Admin