You show no profile. That confuses me.
From looking at the pics you posted, I'm going to guess that there is Not an intake fan on the lower front of this case. It seems it relies on drawing air through the side covers.
Take what Shadowknight posted seriously.
Using sharp side cutters the rear grill should be removed and a wire grill, like the one on the PSU, installed.
If you need to move alot of air quietly. Clean up the hole where the stamped grill was removed and install a 92mm fan externally, using a 80mm to 92mm addapter. In plastic the addapters are <$5.
If you need more intake air. Cut a hole in the left side cover, centered between the graphics card and CPU, just favoring the front of the case. Use a 92mm or even better a 120mm fan.
If that sounds like too much work or you have no tools, maybe a better case is in order.
...Galvanized