Probably a 5 degree drop when I used Push/Pull, it's in a Cooler Master 932 BE. I put another fan in the CD bays.
http://www.coolermaster-usa.com/product.php?product_id=2992
It does get hot in Prime 95, close to 70 degrees. In games, it doesn't usually hit more than 55.
So I have the 240 fan on the bottom front, an extra 120 MM fan in the bays on the front pulling air in
The stock 140mm fan on the back and the H100 w/ 4x 120 MM on the top pulling out of the case.
All the cables are managed behind the case for the most part, so the air circulation is great.