On my Win SBS 2003 machine, the IUSR & IWAM accounts are not IUSR_[computer name] as the computer name was changed in the SBS setup from what it was when IIS was [pre-]installed. I fixed this by saving loVirtual.AnonymousUserName and loIIS.WAMUserName in setIISAdmin, and used those names instead of 'IUSR_' and 'IWAM_' +lcCompName in the section of NewSetup where the temp.cmd batch file is built.

I can post the code if anyone is interested.