the url requested was not found on this server
How did you check that mod_rewrite is enabled for sure?
I would say you try this: backup your current .htaccess file and create a new one with the following content:
Options +FollowSymLinks
Redirect /google.html http://www.google.com
Now go an visit http://www.showpill.com/google.html and see if it redirects you to google.com
If yes, then mod_rewrite works, if not check in your httpd.conf file that AllowOverride is set to All and restart Apache.