Running an Application through browser

Here’s what I am trying to do:

I have an NT 4.0 Terminal Server
I have an application on this server that I need to be able to run through the users web brower, IE5.
How exactly do I start the application once they hit the server? I don’t want to have to install ANYTHING on their PC. All I want is for them to be able to type in the URL and bang, there is the application started. Help!