as for heat, just let your machine run for a while churning away, then take off the side panel, and do a touch test on each hard drive. see how warm it is, you may need a bigger fan to cool those hard drives. My hard drives are both hovering around 28 degrees Celsius now, with my 80mm vantec stealth running at 1/2 speed. Even when they've been running for hours on end doing video, seldom do they get above 30 degrees. Unless, i leave the fan off.
If you find that they are too hot, and that there isn't much air flow around them, then you could possible buy a 5.25'' to 3.5'' bay converter, (i believe vantec had a passive cooler for hard drives) and put it up in the optical drives bay. That passive cooler was a converter, but it also had heatpipes to cool the hard drive.
ECS L7VTA mobo
2 x 512MB DDR400 Geil Value Ram (w/blue hs)
NVidia GeForce4 MX 420
Seagate Barracuda 120GB, 7200Rpm, 8MB buffer (pata),
Seagate Barracuda 160GB, 7200Rpm, 8MB buffer (sata-ncq)
BTC1108IM dvd writer (8X)
Aopen 1648 dvd-rom
sunbeam fanbus controller
Philips 190X5 19\'\' LCD monitor 12ms