One more Vote for EasyPHP. For viewing a PHP file on your computer, you need them to parse through PHP and MySQL Server. You also need Apache or someother Web Server.
Simple Way, would be...to just install EasyPHP and then you paste you php files in C:\Program Files\Easy PHP\www.
Then run Easy PHP and point to browser to
http://127.0.0.1 and you can run your PHP files from there