Wow, somehow I completely missed this case. It seems a very good base for a build - and you did it! Yes, from the pictures it looks very functional too. Although there may be some room to improve...
I'm trying to understand your wc loop. It's clear that you have a single loop. What's the direction of the coolant flow?
1. Res/Pump(s)-CPU-top Rad-VGAs-bottom Rad-Res or
2. Res/Pump(s)-bottom Rad-VGAs-top Rad-CPU-Res?
Your top Rad is a 3x120(140?) one, the bottom is a 2x120 - correct? Now, which of them is mainly cooling the CPU and which of them is cooling the VGAs? Not sure how hot the new 7970s are running, but I assume that together they are quit warmer than the CPU alone. So, cooling the VGAs with the triple Rad would have more sense - having the coolant flow direction as I depicted above in 2nd case.
Have you been thinking about placing the bottom rad vertically? I mean, on it's side - to pull air from one side and push through other side. Of course, you would have to cut the side panels... But, this way you could avoid the hot (ok, let's just say warm - anyhow, higher temp than ambient) air leaving the bottom Rad to be exhausted into the case. Additionally, you could have your drain port at the lowest point of your loop... (right now is hard to drain the bottom Rad).
Overall, i think this is a really nice build, specially as a first water-cooled project! The questions/ideas exposed here are just my thoughts, driven by curiosity and willingness to generate some experience for all of us...