Hitachi Travelstar (120G) decided to vanish

My computer initially loved my Hitachi- they got along great. All of a sudden (and I mean sudden- it sounded sick one day and died the next), it decided 'to hell with this' and the computer detects that there is something plugged into the USB port, but decides that it doesn't want to display the drive in the My Computer window, or even in Explorer. It just doesn't want to. I've tried uninstalling and reinstalling the driver, switching external HD cases to make sure it wasn't just the case, switching cables, using the cable with the two ends (you know, for powering the drive on a USB 1.0) and even smacking the thing, like we did with the TV...I kind of wonder if it had been dropped, so I hit it (lightly!) again, just because after going through everything else that should have worked, it seemed like the last resort thing to do.

There is a lot of stuff I'd rather not lose on this drive- including all the backup copies of my extensive CD collection- I am a dance instructor and it is so much easier to flip through MP3s than it is to dig through stacks of disks. Any help in figuring this mess out would be greatly appreciated- this is frustrating, as I was using this drive regularly, nearly daily, before it died. It and I were friends, now it is stubbornly refusing to work. Just y'all wait, now that I've posted this, it is going to suddenly decide to be my friend again (I hope).

The computer it is running on is an Averatec 7100 running XP pro. The model number for the drive is HTS421212H9AT00 (120G) and it is being used as a USB 2 external hard drive. If you need other information, please ask!

Cheers!
~Anna.

ADDITIONAL INFORMATION:
The drive does make noise when initially plugged in- it isn't so much a click, but a "zzzp...zzzp...zzzp"- almost like something in there isn't getting turning.... I know, terrible description...but it's the best I can give you. Hope it helps.

I've continued my exploration of the computer and, in device manager, when telling it to display hidden devices, it pulls up a list of non plug-n-play devices, one of these says "Serial" and has the little exclamation point next to it. I wonder if this has something to do with my problem. When I click on it, it tells me that the device is not working properly or it does not have all it's drivers installed. How on earth do I fix this?

 

Apologies for the double post- the edit button has disappeared....

I tried plugging in another one of my external drives- it is another very similar drive- same company, different model (this is only a 30G) and it is working fine...but the little exclamation point is still next to the hidden device "Serial".