Dawa,

Be aware that this is per application only - because WindowsXP isn't running IIS 6.0 the worker process was an added layer in order to accomplish some of the needed functionality required for asp.net... For Windows Server 2003 which is running IIS 6.0 you can setup application pools which can run a whole set of asp.net application under a particular identity.

What Dmitry gave you works but it may not be the behavior you want when deploying to a Windows 2003 Server... Just food for thought.