Hmm... OpenOffice's minimum requirements are a bit below what that has, although it might work. (And is free and of course very full featured.) I would assume it would run better than Neooffice (which is just using OpenOffice's code but I think doing kind of a Java implementation rather than x11).
I bet an older OS 9 version of Word might work-maybe Word v.X? Looks like even Word 2001 (for OS 9) has higher system requirements (more RAM anyway).
EDIT: Honestly if those don't work, Text Edit is fairly full featured too if I'm remembering right. I mean it has spell check and basic formatting, so might be good enough to work on from the Powerbook, and then just open it with a full word processor when working on it on a different computer. (Depending on if you're mainly just worrying about the content of it versus fancy formating.)