what version of QuickTime are you installing with itunes 6?
Your error message indicates that your version of QT is NOT 7.0.3. So, go to the Apple site and download QT 7.0.3 for yourself.
It might work
i installed and reinstalled the itunes 6 and quicktime package several times, but i keep getting an error message saying i need to intall 7.0.3 whenever i try to run itunes. help would be appreciated.