Page rank is not at all related to actual rankings of your website. On most of the occasions it is observed that websites with lower page rank overshadow websites with PR5-6.
Try to concentrate on the actual rankings of your website. Try to do everything which makes your website popular naturally. This will help you gain higher rankings on search engines. Concentrating your entire efforts on PR alone will only dissapoint you in the end.
The best way to proceed is to follow a natural optimization pattern without worrying about PR. Both Google/Yahoo uses hidden parameter known as "Trust rank" which decides the ultimate rankings of your website.