5 minute install running into overtime

I’m trying to get WP installed on my site. I’ve made my way through items 1-4 on the 5 minute install list –

define(‘DB_NAME’, ‘jasonpedley_com’); // The name of the database
define(‘DB_USER’, ‘jasonpedley’); // Your MySQL username
define(‘DB_PASSWORD’, ‘password’); // …and password
define(‘DB_HOST’, ‘localhost’); // 99% chance you won’t need to change this value
define(‘DB_CHARSET’, ‘utf8’);
define(‘DB_COLLATE’, ”);

…but when I got to open /wp-admin/install.php, my browser (Firefox) wants to open the file as if it were trying to download it as opposed to simply taking me through the install script. Oddly enough, the icon for all the PHP files are the Dreamweaver icon.

What gives? Any advice?