from PHP3 to 4 in 1 difficult step

I am trying to upgrade from PHP 3 to 4 with no luck I am running 98 with PWS and php 3 which works fine. I have put php4 in c:/php and edited the .ini correctly as php3 and that worked so I can't work out what's wrong. DLL's in windows/system as well as c:/php! php4 reg file has only 1 entry compared to 3?!? any comments. Anyone else successfully moved from 3 to 4 easily? any tips? Have you got both running together? I can't seem to find any online win 9x specific upgrade info. Best regards Scott