Help with IIS and rewrite?

I have recently gotten Drupal to work on my laptop, using the Zend Interactive Development Environment (with debugger), and Microsoft's IIS server. I'm working in this way because the Zend debugger requires a host-based debugging routine that my shared hoster will not load for me, but since I've headed down this path, I also can do development while I'm at my daughter's soccer game :)

Everything seems to be working great EXCEPT for using clean URLs. When I enter something like http://localhost/drupal/index.php?q=forum, it serves up the forums page just like I'd want. But if I just enter //localhost/drupal/forum, I get a timeout on the Windows-based IIS implementation. I'm suspecting that this has something to do with rewriting on Apache vs IIS, but have NO experience here. Can anyone perhaps shed some light on what I'm seeing, and if possible, what I might do about it?