Compared to the instructions at http://customerfx.com/pages/crmdeveloper/2008/02/21/solving-thttprequestthread-errors-with-activemail-in-saleslogix-web.aspx there are a few different steps to get the SLX Mailmerge piece to work on a Vista web server (IIS7).

• Configure the web manager, same as on 2003 or XP (same as the instructions on Ryan’s post)
• Create the /mmserver virtual directory and point it to C:\PF\SLX\Web Components\mmserver (same as before).  Make sure you create it as an Application and select the correct type of Application Pool (classic pipeline, 32bit enabled if running on Vista64)

• Under mmserver click "Handler Mappings" and enable "ISAPI-dll":

• On the server configuration (click on the server name), select "ISAPI and CGI Restrictions" and add an entry for the slxwebmm.dll:

Update (2008-08-23): Same instructions work with Windows Server 2008. We had to make sure that the mmserver and the SlxClient applications were both running in the same application pool for some reason.