Your HD bay is at 52 celsius? I think that's getting a bit high for a hard drive. But then my iMac isn't a fair comparison, I'm in a fairly cool room with the fan on and my HDD fan is at 2000 rpm.
I downloaded iStat onto my old old G4 15" i-Lamp. Funny, it doesn't seem to show the temperature. Is this because there are no temperature sensors on this old model?