So I finally managed to get a C series Zaurus from conics.net. Ironically, just a few weeks later about 5 C-series zaurii come up on ebay UK, including 2 C750s which went for half the price I paid for mine and came with accessories as well.

Anyway...
I think the battery on mine is not as good as it should be, so I need a replacement. I'm thinking of trying to get the large battery, such as the C760 and C860 has, but where can I get one, and more importantly, where can I get the cover for it?

Thanks
Simon

Conics has them. (Surprise!) You can get the battery and cover as separate items (good if you're happy with a cheaper generic ebay battery), or as a package.

Pulster in Germany has them

Hmm- that's a lot of money for a plastic cover.

Am I supposed to be able to change the battery in my Zaurus when it is suspended (i.e. without having to reboot) or do I have to connect external power?

You really, definitely need to be plugged into AC if you want to pull the battery and don't want a reboot, it's not magic

Well when it's suspended only the RAM needs power so it wouldn't be difficult to do.