overheating really isn't an issue with those drives. and pretty much anything will work, maxtor, western digital or seagate are ones that I would recommend. get a 7200 rpm drive.
My experience with external HDD is to purchase the ones all ready pre assembled. Buying a drive and then an encloser is not the way to go. Not all drives will work with all enclosures
...the Iogear seems to have some pretty good ventilation on the top, but I can't be sure... does anyone have experience with 4200 and 5400 RPM external HD's?
I have a Maxtor, but it's ventilation system doesn't look that good... they're the same weight, but the Maxtor can lie on its side, not just on it's bottom, like the Iogear...