Check these out, they seem to be the best you can find, I'm getting one very soon but have seen them in person. Lot's of room and good air flow in the design. Here is the link...

Some of them here

I'm using a rackmount case I purchased from one of the local wholesale computer suppliers. Ever since I went from the tower to the rack, I've noticed a very big difference in performance too (although I did upgrade the MB & Processor). I like the fact that this contributed to the over-all performance of the machine. It has a crossbar w/ dual fans inside as well as a large vent type fan located in the front grill. No major problems here.