I can see my external hard drive in device manager, but not in my comp

Recently my sisters system began to slow down dramatically (most likely due to a virus), until one day it wouldn't boot at all because it couldn't find a hard drive on her system. I reconnected all the cables, which didn't work, so I took it over to my system thinking it might be a bad cable, but it wasn't, and so a friend loaned me an internal HDD to external HDD. After I plugged in the USB cable, I was notified that a Mass Storage Device had been connected, so I went to My Computer and it wasn't there. I checked in Device Manager, however, and it said it was working fine. I couldn't see it in Disk Management, so after looking around for solutions, I found that when I went into my registry, went to Mounted Devices and found the "DosDevice" that said "U.S.B.S.T.O..." (USB storage) and renamed it with another drive letter, I could see it in Disk Management. I was then able to see it in My Computer. When I tried to click on it, though, it said there was an I/O device error. Since it was 2:00am and I had already fixed another unrelated problem on another computer that certain people *cough* had neglected to mention until 10:00pm, I went to bed figuring I would use data recovery software to try to save as much data as I could from the hard drive. However, when I got up this morning and went to work on it, I could no longer see it in My Computer (though I could see it in Device Manager), hence I went to the registry to try what I had done earlier. Except, U.S.B.S.T.O.... was no longer there. I have older versions of my registry that don't help at all, and neither does using System Restore. At this point I'm back to square one. I'm betting this hard drive is simply screwed and trying to get anything off it without going to a recovery specialist is a lost cause =P. If anyone could help with this it would be greatly appreciated. The system I'm trying to fix it on is Windows XP Pro w/ Service Pack 3, and the hard drive in question is an IDE 20GB Western Digital Protege. I've tried using different jumper configurations, but to no avail.
Thanks.

I only use A to E right now. I tried connecting the hard drive as a slave before I even had the internal to external converter, but I still had no luck getting it to show up.

Humm. IDE 20GB Western Digital Protege !
seems to be a very old HD, used a lot and maybe dead forever.

Try to Google "repair a broken hard drive"

They weren't really important, it's just that obviously any loss of data isn't fun =P. Thanks for the advice all!

If you can see it under Device Manager as working and not in My Computer at all you will need to undo any partition and then do a quick format to get it to work. You should also notice the LED not flashing before you do this. I JUST did this to two different HD's. One was a Passport and the other a My Book.

I right clicked on My Computer, clicked on Manage, then on the left you will see Disk Management. Click on that. You should see ALL of your HD's as well as your Burners. Right click on your "broken" HD and delete volume. It should go Unallocated. Right click on Drive again and format with a quick format since you have no data on it anymore. It should work. Good luck!

My LG external hardisk is getting worst, I couldn't see it even in my device manager. I have lots of important files there but my external drives does't show in any computer, it only lights up indicating that it is connected and working but actually it's not.

Could someone tell me how to work this out? I need my files in there asap. Please advice...