Stick the restore CD/DVD that came with the machine in the drive and run the Install Bundled Software program. Will install iLife etc without installing OSX 10.4
Also i have another mac (mac mini) setup, can i drag the applications such as iphoto etc onto an external hard drive from the mac mini and then copy them to my powerbook? Will the apps work? Is this legal to do?
The apps will copy, but GarageBand loops, iDVD themes etc will not get copied. You could copy them from their locations in the application support folder, but using Pacifist as linked above would be better.
As long as you have 2 licenses for those versions of iLife this is legal, but if your Mini shipped with newer iLife than the Powerbook it's not legal to copy the newer version over.