Using a G4 Power Book Laptop iTunes as a mirror image of my G5 iMAC iTunes

I am a DJ utilizing my laptop to play iTunes at gigs, while using my Desktop iTunes at home as the source and working center to add & delete Tunes, and compose my playlists for upcoming gigs. My Playlists (and Tunes) are composed of many different type files- MP3s, AIFFs and AACs from different sources, including my own creations from Garage Band. I use a Firewire to transfer my entire iTunes folder (including the 2 Library files) to effect a "manual synching" or mirror image between the 2 machines periodically. This worked well for a while.

Recently, when I last did this, the laptop iTunes would not play all recently revised tunes. I had to point the way to the individual folders for dozens of my Tunes, eventhough they are all in the same Album folders within my iTunes music folder as they are on the source iMac. I was OK with it, until I updated the laptop again right before a gig, and the same thing happened- putting me into a panic.

I have setup iTunes Preferences exactly the same between the 2 machines. I am using 7.7.1 because the laptop Powerbook is a G4 running with 10.3.9, and will not run iTunes 8, while my desktop iMac is running under 10.4.11. I repeat, I am using iTunes 7.7.1 on both machines.

Anyone in a similar situation that was resolved? I would even try suggestions.