Honestly,
I think that the best solution to this problem is to get one of the Samsung Digimax battery packs that Trisoft sells. That's what I use with my C700. The Samsung works with a dual-voltage mains supply which charges the battery pack. Then the battery pack charges up the Zaurus. Both can be happening at the same time, i.e. plug the Zaurus into the battery pack and the battery pack into the mains, then use the Zaurus like a desktop for hours and hours.
When I fly to America, I find that the Zaurus plus Digimax lasts long enough to pass the time on the long flights. I haven't measured it but I think the combo is roughly 5 times the capacity of the Zaurus alone, i.e. the Digimax holds about 4 charges.
