apache.org....
Apache or IIS is very important, with out it... you don't have a server. It is the backbone to the HTTPD server....
WAMP stands for Windows Apache mySQL PHP
LAMP stands for Linux Apache mySQL PHP
I honestly don't trust any of the "preconfigured" setups (like WAMP or XAMPP) since I haven't had good dealings with them.
I find it better just to download Apache, download PHP, download mySQL.
Install Apache using the installer (the one with "no-ssl" in the name). Unzip the PHP files into C:\php (or wherever you want, just remember the full path). In Apache, open %APACHE%/conf/httpd.conf and the Document Root sections. Go through and continue editing what you need (most important to start is the DocumentRoot info, and possibly the extensions you want). Then, add C:\php (or the path to PHP) to the windows Path in environment variables (Right-click "My Computer" --> Properties --> Hardware Tab --> Environment Variables). Edit php.ini-recommended and save as php.ini. Install mySQL from the installer.
That's it... can't be any easier....