php4, Win, PWS Intall Problems

My development system is running MS-Windows (ME) and MS-PWS (4.0). Am trying to upgrade to from php3 to php4 and having problems. Have tried several versions of php4. Last thing I tried was downloading the php4.0.3pl1 Win32 binary (the CGI-only one with the installer) and ran it. Seemed to go fine. Registry mapped .php and .php3 files to my php.exe executable (e:\php4\php.exe). php.ini is in c:\windows. php4ts.dll is in c:\windows\system. But when I try to execute any *.php or *.php3 files, I get an error (HTTP 500 Internal Server Error - The page cannot be displayed). What could be wrong? Do I need to set doc_root or something else in php.ini? Do I need to put e:\php in my PATH? Is this failing because I had php3 installed before? Any help would be greatly appreciated. I am desperate. Thanks. Kurt Bertone webmaster@cogroupinc.com kbertone@bigfoot.com