Rob Allen has posted a look URL rewriting in IIS 6 (similar to mod_rewrite in Apache) without the URL_Rewrite module that comes with IIS7.

IIS6, which ships with Windows Server 2003 does not have this module though and guess which version my client's IT dept run? As usual, they wouldn't install ISAPI_Rewrite or one of the other solutions for me. In the past, I've simply written a new router that creates URLs with normal GET variables, but this is ugly and I wanted better. One thing IIS6 does let you do is configure a URL to be called upon a 404 error, which then allows you to have "pretty" URLs and be able to route them.

He walks you through the setup of the manager to create this 404 routing setup allowing a single script (an index.php) that uses an instance of the Zend_Controller_Request_Http component to grab the request and forward the page back out to the user's desired location.