i will tell you how i`ve done my configuration (because i am working on a forum right now and i went thru this already). i use apache,php and mysql. so first you have to download this . then you have to edit the conf/httpd.conf (from the apache root dir). you mainly have to edit the root directory, and add at the begining of the file these lines:
ScriptAlias /php/ "D:/php/"
AddType application/x-httpd-php .php .phtml
Action application/x-httpd-php "/php/php.exe"
of course replace the directory with the right one(where you installed your php). i don`t remember of any mysql configuration, except the username and password. that`s about all you have to do.
ps. you must edit the php.ini-dist (the root directory), rename it to php.ini and copy it to your c:\winnt folder