I tried to get php4 to work with php_mssql.dll on iis4, but all associated functions are undefined according to php.
I putted the ini file in the correct place, uncommented the 'extention=' pieces, set a correct extention path for a change, but nothing will work.

I use the cgi-executable version of php (because the isapi version crashes itself in combination with iis4, at least on my machine)