tedster - 7:38 pm on May 10, 2010 (gmt 0)
As a general rule, Helicon's ISAPI Rewrite for the IIS server [isapirewrite.com] now uses the same syntax as Apache's .htaccess. That means you can use Regular expressions for URL rewriting. However, I haven't been hands-on with this kind of query string issue, so I can't be 100% sure what works in this case.
I'd suggest beginning a thread in our Windows IIS forum [webmasterworld.com] for more experienced advice.