I have a full tower case.

At first I screwed all 4 HDs right on top of each other. But I became concerned that they were overheating. So I spaced them out, with an empty bay between each HD. But that takes up a lot of room !

Is spacing them out really necessary ? How have you suceeded with RAID ?

I am using (4) 7200 RPM, ATA100, 8MB Cache, 80GB HDs, set up as RAID 0+1