The N800 is not a good device for listening to Audiobooks. None of the current media apps for the N800 have a "resume" function so every time you stop listening you lose your place. (This includes Canola)
The Garnet VM does not allow access to the SD card so even if you ported your .aa files to mp3, there is no way to listen to them as the Palm Desktop will only let you install mp3 files via Hotsync to the SD card. Pocket Tunes does not work on the GVM ( in spite of what it says on their web site).
So.. if you are like me and thought that the N800 would be a great device to listening to audiobooks you will be disappointed. I still use my Palm Zire 31 for audiobooks.