i beleive you mean sprockets and chain compared to belts and pulleys not sure what one would be best but i beleive you can get a higher amount of teeth on a pulley for the diameter than a sprocket.

i am firmly against tabs, mainly as i can't use expose with them (one of my favourite features of a mac) but also as it insists with opening 12 small web pages that i've visited recently instead of opening google (my home page). the opening of 12 mini web pages often crashes my computer aswell