URL Of Current Page

I am using an include for a navigation bar, This nav bar appears on many different pages and the help facility a button on the navigation barneeds to launch a help box relating to the page it is included in.

The help files are .html but the file names relate directly to the asp page in which the navbar is included. To get the javascript in the navbar to correctly display the correct help window, I need to get at the page name. I am using

dim thisPage
thisPage= request.ServerVariables("URL")

This will hopefully return me the full file path of the page that the navbar is included in. I then need to take the filename out of this URL and remove the .asp from the end so that i can use it in my javascript function to open the corresponding .html help file.