2.8 Installation – 500 Internal Server Error

I have been working with my ISP administrator for a while trying to access the /wp-admin/install.php after uploading all files into my separate blog file on the server. He has confirmed the PHP is up to date. He has tested my database name, user name, password. According to him, we have done exactly as per the instructions given in the ReadMe file and I still get the 500 Internal Server Error. I don’t have an hpaccess file anywhere (advice from previous forum).

Please help (I’m note a programmer so be kind).
Thanks