[themes] Fixed navigation theme for drupal

Hi, I am looking for a theme with fixed navigation like http://webdesignledger.com/inspiration/22-examples-of-fixed-position-navigat... My website is in Drupal 6. Is there any chance there exists such a theme out there ? If not, how much effort it is for someone to build one with litte CSS experience and zero drupal theme experience? thanks -- Nitin Garg