a little bit of advice about the whole positive/negative airflow question, negative pressure is your friend.
it might help if you guys took a look at pHaestus's article "5 myths of cooling", that covers this very issue. also, i can vouch for it from experience. I built a case that was almost completely sealed off except for the fan holes, and it is definately more important to be sucking out the hot air than to try to force air in. also, it has been said numerous times around here in the push vs. pull debate on fan mounting that fans are more efficient when pulling air through a rad than pushing (i think you only get like a 40% increase when both are used) and the same thing applies w/ the pressure in a computer case. with the fan setup on the computer i mentioned earlier i noticed the most improvement when i added exhaust fans (if you've got hot air coming out of any of your exhaust fans, it probably wouldn't hurt to add more) and when i cranked the front fans up and switched over to positive pressure in the case it did nothing for my temps, only blew air out of the drive bays (which is covered in the article here at procooling) so if you're at all concerned w/ how quiet your pc is (ie, trying to use as few fans as possible) it would make sense to use them as efficiently as you can. anyway, my $0.02
*edit* oops, didn't see fhorst's post. i agree, sounds like a good fan configuration. even better if you've got some voltage adjustment on those suckers. btw, how are the evercool fans? i've been looking at maybe getting those (i'd get a blower but i'm pretty sure that won't fit in my case)