2 or 3 fans?

I've been thinking about getting another fan for my case, just because, well, I can. Plus, CompUSA is going out of business so I figured I'd check out their stock to see if I can get one for cheap(er). I have the Cooler Master 534, got it for $40 shipped and then sent in a $15 MIR. Anyways, the way it is now is that the side fan is intake and the rear is exhaust. Should I get another 120mm fan for the front as a second intake? It would go on the bottom. The non-plus version (I have the plus version) comes with a front 120mm fan and no side fan, so I know one will fit there. But is it worth it? Will it provide any extra worthwhile airflow?

Oh, and the system I'm building is on its way, so the only part I have is the case. Going to have 1 Hard drive, 1 optical drive, E8400 with stock cooling, EVGA 8800GT 512MB (I read this gets quite hot). So I want to keep this all cool so it lasts me a while...

Don't know what CFM & Noise your fans are ... but I reckon you'd get best results with:

Back exhaust = High CFM / High Noise fan
Front intake = medium-high CFM / medium-high noise fan
Side intake = low CFM / low noise

With front and back on a fan speed controller so you can silence them when required.