All 'newer' HDDs work with 7200 rpm and get very hot.
Hmm... I wouldn't really call this hot, either... A 120GB Western Digital S-ATA 7200 RPM with no active cooling on it, other than (closed) case airflow.
Local Temp is the CPU core. (P4 3.0C HT)
Remote Temp is (I think) chipset. (Intel i865PE)
HD1 is the hard drive (shows as 1 because it's on the SATA bus.)
Temp 3 is case temperature.
I don't think Temp 1, Temp 2, or Temp 1 (again) are hooked to anything.
And these readings are from a room that is currently a rather sweltering 27C.
With some strategically placed fans, a little ductwork, some good heatsinks, and artic silver, you can keep the most notorious hot-running rigs cool, even in adverse conditions.
What was the point of all of this? Well, I'm not sure. I got derailed somewhere. I think I was just trying to say that you should go for the hard drive you want, and if you're concerned about heat factors, get some monitoring going, keep an eye on your temperatures, and think about case layout for a day or two. If the temps are higher than you'd like to see, add some more cooling to some strategic location.