Thought I would share a similiar problem and the solution I found.
Problem:
I have the same problem on my G4 PowerMac. Everything was fine until I installed iLife5. I did all the normal maintenance, even uninstalled and reinstalled 4.7.1 and have the same problem. If I temporarily move my iTunes library (to exclude that issue), I get the same problem. It seems that iTunes itself is just crashing on startup no matter what I do.
Solution:
Found my answer. When I disconnected by 3G 20G Ipod, iTunes loaded ok. When I connected the FW cable, iTunes quit unexpectedly. It is repeatable.
So, I downloaded the latest Ipod Updater and reset my iPod to factory settings. When I plugged the iPod back in, the iPod reloaded by songs and all was fine.
Thought this might be helpful for someone with a similar problem.