as long as you have a decent amount of air going through your case, then the large passive heatsink that's on your board would be just fine. i wouldn't bother replacing it with a tiny fan that's going to add that little bit of extra noise and has a chance of breaking down in a year or two. not to mention, that little thermaltake heatsink has practically no surface area on it, so it can't be very effective.
but if you don't have any more than one case fan, then the active cooling might be a good idea, if you overclock.
if i wanted to add active northbridge cooling to that board, i would buy my own 30 or 40mm fan and find a way to attach it to that large heatsink that's already on it. now that would cool it down. definitely be cheaper, too.