Easier way to associate iPod with Library?

I have always had my iTunes Music Folder on an external hard drive – when I got my 1st 20 GB iPod, I was using an iMac G3 with a 12GB HD, so I bought an external Firewire HD just for that reason. I have moved this external to an iMac G5, and to my current Power Mac G4 (with major upgrades to processor, video, RAM, etc.), all with no problems. I have upgraded my iPod to a 60GB Color model in between all these moves, and have never had problems associating the iPod with these various computers. I recently (last weekend) upgraded the internal HD on the Power Mac G4, and installed OSX on it – then pointed iTunes to the Music Folder on the external and updated the Library. No problems so far. Then yesterday, I imported 2 new CD’s to iTunes and tried to transfer the new tracks to my iPod – and I get the message about how this iPod is synced to another iTunes Library, and do I want to erase the iPod and sync with this Library. The only thing that has changed is the internal HD with the controlling OS and iTunes (7.4.1 – yeah, I “upgraded”) – the Music Folder is still on the external HD. Isn’t there an easier way to associate the iPod with this new Library other than erasing the iPod and copying back the music? I don’t remember having to do this nonsense in the past with older versions of iTunes. There’s only 2CD’s worth of difference between the Library and the iPod – and the problem for me is this – the Power Mac G4, with all it’s upgrades, is still a USB 1 machine (no problems for most things, like CD & DVD burning and external HD's, since Firewire 400 is more than adequate, but the dock iPods only use USB). Copying 6,000+ songs via USB 1 is going to take all night (plus all the stuff that can go wrong with a file transfer of that duration).
Any ideas?

Robert