Hmmm.. are you saying then that you are using IIS? Some folks still choose to use Apache on Windows NT.

If you are using IIS, I know if provides unique ID's to all ASP scripts -- it's possible it does the same thing for Perl.. although I couldn't tell you how to determine that info. But perhaps that'll give you a start. It may even be provided to you in an environment variable or with the request string.
-Eric