Wow, with the amount of hard drives you have stacked up together and close like that, I sure hope they don't overheat... (I've had 3 drives do, and they wrre just in a plastic caddy...seperate)
the four drives from the bottom have fans on them which keep them quite cool. i have motherboard monitor and it says SMART HD is at around 21 degrees C. whihc i persume is one of the hardrives but oyu can also feel the difference between the four at the bottom and the top two above them. The hardrives arent full to the max apart from the 2x 250G ones. the 300G is about 3/4 full and the 120G is for downloading stuff onto and excess things like software that ive downloaded (that isnt installed) pictures game patches etc
I started out with a pre-made system that was:
amd 3000+
x600 pro AIW
MSI mobo
HIPER 525w
1G Corsair
and the same case which i have modded from this: