MSSQL/PDFLib problem

I am having problems installing PHP 4.2.1 on a windows 2k server box. I unzipped PHP, set-up PHP.ini and did everything else fine, downloaded PDFLib, stuck the appropriate DLL in the extensions folder, but I get errors when I restart IIS (spose when PHP checks out all its files). Unable to load dynamic library 'c:\.....\php_mssql.dll' - The specified procedure could not be found AND PDF: Unable to initialize module Module compiled with module API=20010901, debug=0, thread-safety=0 PHP compiled with module API=20020429, debug=0, thread-safety=0 These must match The DLL i copied over for PDFLib is the version for 4.2.1 and MSSQL client tools have been installed on the computer Thanks for your time --Ben