Now he's bought a new drive altogether, and asked me to transfer the data from the old drive. (Should have pulled it off at that time - oops! ) We ordered a 'Y' cable to try to provide it with more power on his computer, and tried it again on his.
I plugged it into my computer (Vista machine) to see what the problem was and it worked fine, and I was able to access all the data. Recently, I offered to find out if it could be repaired/replaced. At this point, I think it's about two years old.
He did not attempt to get any warranty service on it. He said it made a clicking sound 'like a horse galloping' and stopped using it. My dad had an external hard drive (Maxtor Personal Storage 3200 250GB) that worked with his old computer, but when he got a new computer (XP machine) it didn't work anymore.