The 500 error is easy: remove the .htaccess file
To install the tables using phpMyAdmin, just load up phpMyAdmin and choose your database from the drop-down (if necessary). Then, on the right, you should see a tab called "SQL". Click on that. A large text-area should now be available. Copy and paste the contents of the mysql.initial.sql file into that text-area (use mysql5.initial.sql if you're using mysql5). Then click "Go" or whatever the submit button is, and your tables should be made!!
Make sure you edit your main.inc.php and db.inc.php files as well.
