*bounces* I got it, I got it!!!!!!!!!!!!!!!!!!!!!!!
Ok - here is the problem. You had a .htaccess file in your system directory, it contained a mod_rewrite that was causing everything to look at your main index.php - so you were essentially visiting your site without running update.php and you couldn’t get to update.php with that mod_rewrite.
I backed up your .htaccess file to my hard-drive and nuked it out of your system directory.
You can now visit update.php and the page will load - I have not clicked the link to run the actual update, because I didn’t want to steal that joyful moment from you. *winks*
Go do it and tell me how it turns out. Go go go go!