I would like to assist your with this .
Please update Quicktime from Software update in the Apple menu , Software update. It will be the latest version for your OSX 10.4.
Once updated , Register for Pro activation if you require extra Quicktime Pro options .
Mainly exporting additions and some simple editing are included with the QT-Pro option . Find the option in Quicktime drop down menu and preferences .
imovie HD version 6.04 is a great choice and last of the versions before the makeover in version 7 http://docs.info.apple.com/article.html?path=iMovie/6.0/en/imv1096.html
Later versions : iLife ’09 Mac OS X v10.5.6 or later .
According to Apple's system requirements iMovie '08 Version 7.0 , requires at least a PowerPC G5
1.9 GHz or an Intel Processor. G4's are not supported, though Apple sold its last G4-based Computers (iBook
G4) 14 months before the release of iLife '08.
However, a system hack enables iMovie 7.1 or higher to run with a PowerPC G4.
imovie Version 7 is to be avoided .
iMovie '09 (Version 8.0) Mac OS X 10.5 (Leopard) requirement is on the other hand very good , and you can use both iMovie '09 (Version 8.0) and imovie HD 6 for there plus points .
So its imovie HD 6 , 6.0.3 or 6.0.4 are your best options , without hacking .
I hope this helps .