i've got 2 BenQs and 2 seagate hard drives (250gb and a 300gb inside my case at the moment so you can imagine how toasty it gets in there. I generally leave the side of my case off and I have a clip on desk fan clipped to the top edge of the case pointing inside. (I'm afraid to even connect an extra fan to this 4 year old PSU that only came with a 60gb hard drive and a dvd rom drive as its stock hardware)
also, i organized the case to wires and ide cables weren't all tangled..i figure that has to improve airflow.
I also removed my floppy drive since i never use it anyway.
if you think it's getting too hot in your case use a program like everest home edition to monitor the temps. Mine were never outrageous, but they showed on the higher side for the operating temps of my devices.