Make sure you can still get a battery for it. Odds are that if it saw quite a bit of battery usage, the one that comes with it probably won't power the system all that long.

I just bought a new battery for my Powerbook before my Europe trip, as the first one has already lost 40% of it's capacity since last September. From the number of times I discharged then recharged it, it actually held out pretty well. My mothers laptop on the other hand has seen very little degration, as she rarley uses the battery.