Tiny holes vs one BIG one
A good way to increase the cooling in your case is to increase the free area of the fan openings. On a lot of cases, fan grilles are created by punching out lots of little holes or slots, like this:
http://www.multiplaycity.com/service...holefrontt.jpg
If you've ever run a fan that is not mounted in a case, you'll notice it can blow a fair amount of air. However, put that against a bunch of tiny holes and the fan has to work harder to blow air, because of the added friction, turbulence, and reduced free area. The solution is to take a Dremmel or other similar cutting tool and cut out the grille so it's just one big hole like this:
http://www.multiplaycity.com/service...hedrearfan.jpg
This increases the free area by over 100% and gives you more cooling with less fans. Noise is also reduced since the sound of air rushing through 100 tiny holes is eliminated.
You can add the wire grille for a finishing touch, or you're worried about foreign objects, kids, pets, etc from poking their paws in there. You can find these grilles at electronic shops or on the web.
