For future archeologists mining the forum, we were able to make texis work with IIS 7. We added a new setting, exe-IIS-prefix, that is now standard with Webinator installations.
To clarify, texis CGI in IIS 7 can work out without an update (and did for the customer on a fresh box). If the SCRIPT_NAME/PATH_INFO problem mentioned above is encountered, a texis update now has the ability to handle that situation too.
