This assumes contents of php-4.0.1pl2-Win32.zip were extracted into C:\php4
The DLLs that need to be copied to the System or System32 folder (depending on Win98/NT) are MSVCRT.DLL (it may already exist in there) and PHP4TS.DLL.
Copy php.ini-dist to C:\Windows and rename to php.ini.
Modify php.ini as follows:
include_path = C:\php4
extension_dir = C:\php4
Modify httpd.conf as follows (in proper places):
DirectoryIndex index.htm index.php
#makes it possible to have php index pages
ScriptAlias /php4/ "C:/php4/"
AddType application/x-httpd-php .php
AddType application/x-httpd-php .phtml
AddType application/x-httpd-php-source .phps
Action application/x-httpd-php "/php4/php.exe"
#I've seen the Action directive left out the most. YOU MUST HAVE IT!!!
Cake.
-Abe