Previously workign external HD now NOT working

I had bought a pc from HP a few years ago, and it came with a 52gb hd in it already. (I dont know what make/model it is unfortunately, though if someone could give me a heads up as to how to find out, I would post that info) Recently, I did a major computer upgrade, and had that harddrive made external, all the work done by a local computer store, that we've gone to for awhile and all, and the computer has been running wonderful for the past three weeks. So was the hardrive, until this morning. I have on it all of my art, and mp3's, and it is in general a backup device.. except that I am an idiot and didnt actually copy the files over to my new hardrive. So basically, i would rather die than lose everything on there. It is assigned a drive letter, and shows up as working fine in device manager, however anytime I try and acess it, it says that the drive is not formatted, and asks if i would like to do so. There have been no errors whatsoever, and I have uninstalled/reinstalled drivers and done system restore, just to see if that may help. Most problems with the computer i can fix myself.. but this time I am just at a loss. I tried this on the family computer, that's a bit older, and am getting the exact same error

This is/was running on a AMD Athalon 64 3400+ set on a
K8N-E deluxe MB, with a western digital (i think, dont have box handy) 80gb hd, running WinXP with sp2 and all updates. The second computer is another hp made, I dont know specs on it offhand, but its never had any hardware issues, and is also running WinXP sp2. I run virus/adware scan on both drives (my internal and external) daily, and have had no infections since install.

Any help whatsoever, even a ''take it and have the computer store get the data off''. Cause really, I cannot do without the aprrox 25hgb of data on this drive. Years of paintings and work, as well as a good amount of mp3's.. (those are replacable, but i would realllyy hate to have to pay and download'em again, heh ). Thanks!