in the middle of building a new case, ive cut a 750a to fit 120+92mm fans in the front, 92+80mm in back for exhaust, some others not worth mentioning here, but i expect the case to be damned near ambient temp....the 750 is a heavy case, and i got quieter fans (120 delta, rest are sunon), i dont expect it to be too loud, i hope. The fans are all 12v, i can drop them down to 7v if needs be(reduce rpm, noise, which will reduce quicker than flowrate in general), but i dont forsee needing to do that.
....anyhow....
I'd recommend a couple of 80 or 92's in the front, but dont do any mods that you can not revert later. dont know if youre going to get that DVD for xmas or what
if you do add it, make sure you have good flow through the front panel, and that the fan wont be sucking air out of the case and then back in...if you can, put the 120 low, and the 80 high. cooler air will be drug into the case, and your exhaust is probably high, you want to create a cross-case flow (top to bottom), rather than it being sucked in and then right out without circulating through the case first.