So I dug around my program files (I don't have all my program files listed in my Start Menu), and found SpeedFan 4.34. It reports the hard drive as around 145 to 150 degrees Fahrenheit.
79F = ~26C which is a pleasant day here, (Melbourne, Australia), I've never seen my HDDs running, (at the most), more than approx. 10C above the ambient temperature - and usually only 5C above.
Yours are indicating running at almost double the ambient temperature, which indicates some serious cooling problems, (or possibly HDD mechanical problems but one thing at a time).
One thing you can try is take the side panel off of the PC and sit a normal 12" room fan to blow into it and see if that helps. If it does, you probably need to sort out better cooling for your case, video card, drives and CPU.
I see you mention a Pentium D 2.66GHz and then 3GHz: Does this mean it's overclocked and have you tried returning it to it's normal clocking?
When was the last time the PC was thoroughly cleaned of dust, (heatsinks, fans, PSU, everything) ?
And before someone jumps on me - I do not recommend
cleaning it yourself, (especially the PSU), if you're not technically oriented and competent - the PSU can kill you even when turned off and disconnected from the mains.
Oh, if you do feel inclined to clean your PC internals, please don't hold the vacuum near a fan just to see how fast it will spin - it could mean a early death for something.