I wrote this isapi_redirect HowTo a few years ago before I had access to a Windows 2008 host to test with. Here are a few notes to help avoid some commonly experienced issues with IIS 7.5 and the Tomcat isapi_redirect.dll connector:
If you are setting up isapi_redirect to connect to a tomcat/jboss/glassfish server running on localhost, don't use 'localhost' for the worker host parameter, use 127.0.0.1 instead. On Windows 2008/IIS7.5, isapi_redirect can't seem to find localhost even if localhost is explilcitly set in the HOSTS file on your Windows system. Instead, it will log messages in your isapi_redirect log file like this one:
jk_open_socket::jk_connect.c (627): connect to 0.0.0.0:8009 failed (errno=49)
Your browser, when trying to open the URI for the web application, will generate a Service Unavailable message. Switching to 127.0.0.1 solves this.
404 Not Found or Server 500 Error Messages
Place your isapi_redirect.properties file in the same directory that the DLL is located in and the directory the DLL file is located in should not have any spaces in it's name. This should resolve any 500-level error messages when testing a connection to see if isapi_redirect.dll is working. Other configuration files should be in a subdirectory named "conf".
In addition, on any new Windows system you log into, the first thing to do is check to make sure that Explorer is not Hiding File Extensions for Known File Types. I was receiving 404-Not Found messages testing a connection because I had not noticed that Windows was adding a .txt file extension to my isapi_redirect.properties, uriworkermap.properties, and workers.properties files when I created them using "New Text Document" from the context menu.