WAMP server can be downloaded from http://www.wampserver.com/en/download.php and installed as per the directions.
On Installation , you can specify a directory as C:/WAMP for installation path, so that people using VISTA dont have to struggle with Admin rights each time , as is the case if installed in Program Files. Its just a suggestion and you may use any method you want.
Once the installation is completed, open the default internet browser , and type http://localhost or http://localhost:80
WAMP homepage should come up.
In case the WAMP homepage is missing, check the system tray for WAMP icon , right click and select "PUT ONLINE" , or an option that appears to be like that (like start all services) .
Once the homepage displays (http://localhost) WAMP server , WAMP is ready and you are ready to go for your PHP code