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17" PowerBook for me, it's my most powerful PowerPC portable so seems most usable, I'd like something like a 12" G4 iBook with a decent battery but I've not had a single decent battery on any PowerPC device I've owned.

Luckily, if you *do* find one, iBook G4 batteries are still quite cheap- $25-$30 from the usual places.
 
Powerbook batteries are terribly expensive. Its the only (but really huge) drag when owning an awesome 17" powerbook.
 
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