I tried to go through every FAQ (the firmware one was quite enlightening) that I could read that pertained to hard drive crash issues but I'm perfectly capable of missing something or not realizing what I was reading could have solved my problem so be kind to a newbie.

Plus, it seems a lot harder to find information on logical issues rather than physical ones. Anyways onto my issue:
I am in the process of "repurposing" 3 machines since I just built a new box. So, I had backed up all data for the old machines on one hard drive until I had a chance to put it all back. However, in the process of making a ghost of one of the new machine images, Ghost crashed and the hard drive, which was in a USB enclosure, is no longer accessible.
It was a close to full 320GB (~20GB of free space left) hard drive (Maxtor DiamondMax 21) in an external enclosure, being used as a USB hard drive for backups of a few different systems (6 in total, I belive) and I hadn't gotten a chance to make a second copy of all the backup as it hadn't been completely sorted. So, I am looking for as close to total data recovery as possible. Time is not as important as completeness- as I would really like to get as close to 100% as possible, even if it takes time.
I tried to hook it in as a USB, slave it out in one of the other machines via IDE, and tried to read it as a USB drive in Linux (Knoppix) but it could not be seen. In Windows, it shows it as an unallocated drive so it's almost certainly a logical and not physical issue. I have no reason to believe it's a physical issue as the disk was less than a year old and the reason why there is an issue seems to be from Ghost.
I ran a thorough scan on Partition Find and Mount and all it found was 1 39GB partition. Now, I'm a little leary of restoring/mounting that partition as I'm not sure if that will lessen my chances of finding the rest of the data on the disk. I'm a novice at disk recovery mainly because I tended to do good on keeping backups so it was never necessary- a drive died, I always had a good backup until now.
So, in short- I'm looking at a disk that more that likely still has all the data on it but just can't find it. However, I'm not sure where to start mucking into this where I wouldn't just be slogging around, ruining any chance I had at close to full data recovery.
Cost is somewhat of an issue as, since I don't do this for a living, I don't think I can throw a couple thousand bucks at a piece of software to do this once- I might as well have some mailaway service do it for me for half that. But I don't mind paying for a good piece of software that is really likely to help me out, doesn't have a grueling learning curve, and that I would have around for any future "data incidents".
Thanks in advance for any and all help, any suggestions on software and any methods on how to proceed
SI