So I'm planning a similar trip... and I've considered my options. My biggest fear is theft, I'm not too worried about damage. I've traveled with a 12" G4 Powerbook around many places before, including Tibet (didn't get a chance to make it to Everest Base Camp...). I've taken it on backpacking trips, and rock climbing trips to places all over the world, so if you take care of it, damage isn't your biggest concern. Theft is, cause it's one of those things that you can't control easily.... if you travel for 6 months, you are going to lose something...

So with that in mind, I might actually go dig up my old powerbook and bring that along and should I lose it.. oh well.. My other consideration is my current 13" macbook. The reason I'm even willing to consider my current Macbook is I do a lot of photography and need a computer that can process 1,000 pictures a week on (yes.. I just click away.. :)). I plan on having at least 1 WD Passport along for data storage and back-up. Which adds another reason to bring my Macbook, it runs Leopard so it has TimeMachine to back-up my data. But if I lose the Macbook, I'd shed more tears...

As for writing the Great American Novel, I plan on dropping by REI and picking up those waterproof notebooks for the times I'm out in some crazy environment (say sea kayaking in Alaska, climbing Mount Kenya and/or Kilimanjaro, etc...), that way I can leave my laptop safely locked up somewhere...

Another thing to consider is weight. With all the cloth you are bringing.. think about your varied environments.. from desert (100F+) to Everest Base camp (32F-) All the gear you will need for those two very different environments.. where are you going to put it? If you bring an Digital SLR... what about that gear? Lens? etc..

Toughbooks are cool, so are Thinkpads, as are Macbooks... so in the end my suggestion is do the non-geeky thing.. buy small, buy cheap.. and be prepared to lose it..

Drop me a line if you are interested seeing if we have any common destinations...