Well up here in Oregon in the Summer it rarely even gets into the 90s. Would not just the CPU fan and PSU fan suffice?
No, you still need adequate ventilation and fans to circulate the air, otherwise stagnant air will heat, thus causing your components to heat, and you don't want that. I would try to discover which fan/fans are the noisiest and see if you can't swap them with fans from your old case or the other one Doortech sent you. I mean, if this is your main rig and the other cases are spare, I'd cannibalise those for quieter fans to get the best result for the primary beastie. Oh, and be sure to enable Cool & Quiet to help reduce CPU heat.
I see that the CPU scores well in the WEI, which makes me happier that I decided upon the 920 quad core instead of the dual core I first thought to send. In fact, Windows 8 would probably run fairly well on that setup, and I doubt the video card would have much bearing on its performance over all, so if you're not running higher end games it should serve you well for some time to come.