I'll take a photo the next time I take it apart, but it looks very similar to this:
Same case, video card in the same location, and most cables are stuffed behind the motherboard. What you can't see in the photo are the two exhaust fans on top and that the whole front is an open grill.
I've noticed that the heatsink itself stays pretty cool and CPU temperatures don't go up much if I remove both fans. That might suggest poor contact between the CPU and heatsink, but I've installed it twice with two different pastes and followed instructions and recommendations. When I removed the cooler earlier today, the paste coverage looked good. And although I didn't have the screws tight the first time, they're good now.
I had the same thought about trying the new fan as an extra intake, but I had the case opened up at the time anyway without much change in temps, so it didn't seem like an air flow issue. I'll give it a shot when there's a sale on a good 140mm 1,000-RPM fan.