I had the reverse problem (HD Crashed, iPod was ok) and I used this to get everything back on the computer:
http://www.zeleksoftware.com/liberator.htm
I do remember that I had to install iTunes 7, add my un/pw so that it knew it was my account & confirm something as far as the purchased music.
The main site -
http://www.zeleksoftware.com/index.htm - has some other iPod fixes, so you might want to poke around there.