The PowerBook 2000 Firewire (a.k.a. "Pismo") is, I think, the high-water mark of Apple laptop engineering. I bought one of those 9the 400 mHz one) in January 2001 and have been using it as my frontline machine ever since. It was the Apple laptop that did away with all the legacy ports, instead embracing Firewire and USB, and the first PB with a DVD drive. I've watched (NOT enviously) as hinges cracked on the Tis and logic boards failed on the dual-USB iBooks, and I am only now buying a new PB. I have never had a single problem with it in almost five years of daily use and much traveling.
The Pismo was the best Mac I've ever owned (Quadra, 7100, 7300, Pismo, and now the newest 15" PB); no others come close. It was the most rugged, reliable and upgradeable PowerBook Apple ever made and I'm fortunate that I happened to buy it. I've maxed the thing out over the years--G4/550 CPU upgrade, slot-loading Superdrive, 80GB/5400rpm Travelstar HDD, Airport card, and a high-efficiency battery. Only since Tiger have I perceived it as slow--the 8MB non-upgradeable Rage Pro GPU has long been the albatross around its neck. If you're able to get one new in its box after all this time, GET IT. You won't be sorry.
P.S.: If you don't understand why people are gushing praise for the Pismo, you haven't owned one. I'm not spoiling for a fight either, I'm just doing my best to explain the Pismo thing. I cannot say enough good things about this machine, and there is a huge cadre of Pismo-users who are stubbornly hanging onto their machines and upgrading them even though they are now quite outdated. If the newest PB wasn't the last PPC PB, I would hold out even longer, but I want to ensure that I can use my PPC software for several more years. I was just talking with a Pismo user today while ordering some replacement rubber feet, and we didn't have to say much--we both felt lucky to have this laptop. When computers today are starting to look increasingly disposable, this is one of those very rare computers that people can't bring themselves to throw away. Some guy private messaged me about buying my Pismo on the MR forum after I mentioned I was buying a new PB 15", and I laughed him off--you'd have to pry my Pismo out of my cold dead fingers.