You still have the IIS7 Webserver installed, This needs to be uninstalled before installing any other type or WAMP/LAMP Server on your computer

Steps:
Uninstall WAMP - Restart Computer
Goto Control Panel > Uninstall a Program > Turn Windows Features on or Off
Ensure the Tickbox on the following options are NOT selected

+ Internet Information Services (All Sub Categorys Aswell)
+ Internet Information...