I agree, I had major issues with 10.4 as well. I did the same going back to 10.3 and problems solved.
Main issue was the grid version black background with white text one day randomely turned white on gray..and stuck. Wasn't able to make out anything on iTunes whatsoever. Album art? ha that was not happening on that version for me either.
I gave up and went to a better old version.
I had issues with my iPhone/iPod saying the usual "synced to another library"
Using the BU files that are in your "old" library never work - at least it never did for me.
Once iTunes decided my device wasn't recognized anymore trying to restore your music library with a folder from that "unrecognized" iTunes library, never gonna happen.
Same message would pop up "can't find the original file location"
I learned to just compress the latest backup file to a USB to use the next time I get that message.
Once it wipes everything out and the device has synced again ..
I look at the path of where the new back up folders will go, change the folder name accordingly and drop the folder in my new users/library/music/iTunes/BU slot etc. ..
export all the songs to iTunes and my library is filled with all my music.
This has worked each time, luckily!. Just tricking iTunes into thinking it's a brand new folder of music ready to be imported, though it's the same one it couldn't recognize all along.
juzzle - thanks for providing that link! great to have so many versions of apps at your fingertips!