I tend to keep the packages I install from Apple, just incase I need to reinstall stuff, so when I went to reinstall iTunes on the iMac G4, I remembered reading about the error I got when I tried to run the package:
Betalogue » Blog Archive » iTunes 7.3 update: Weird package problem:
It still holds for 7.3.1, and it applied to downloading the package only, or installing and keeping it and then trying to reinstall it again.
