You shouldn't have too many problems with the iBook syncing with the Empeg under VPC. I use VPC under OS X on a Dual G4 500, running Win 2K. The single most useful piece of advice I can offer is this:
1: get the application File Buddy
2: use it to do a search of your mp3 folders for any items call ".DS_Store" and "Icon" and delete them right before you sync with your Empeg. I found that without doing this the Empeg would hang 2-20 minutes into the process.
I have tried JEmpeg in the past, but found it didn't deal with mp3 tags very well; it couldn't even recognize ID3 v2.4.0 tags. Maybe this has changed since last I tried though, a couple months ago.
Good luck, and have fun on your trip!

-Randy