How much does it cost? I mean, is budget a main consideration? One reason I ask is that the Athlon XP-M, while it's got better power management features than the Athlon 64, still isn't as good as a Pentium M in that area, especially a low-voltage one. I've never used a Transmeta-powered machine, but if you can find a machine powered by a Crusoe or Efficeon, you might get even better battery life.
Did you check out the Fujitsu S6000 and P7000 series? How about Toshiba? With the S6000, you can get well over eight hours of battery life at the same weight of the machine you've posted, and it's got a better screen. With a single battery, it weighs two-thirds of a pound less. The P7000 series, IIRC, has a wide-format screen and is (at least one of) the smallest in the world to feature a DVD burner option. Fujitsu laptops are known for being pretty rugged, too.
I don't believe in buying things you don't need, but if it were me, I'd spring for Windows XP Pro, even if I were mainly going to be travelling with the machine. You never know in advance how you'll be using your machine two years from now.
Good luck with your decision. I'm sure that no matter what you pick, you'll pick a machine that can get your work done and store enough data. The main factors for me, in a thin-and-light, are whether the screen and keyboard are easy to use, and battery, battery, battery. Plugging in isn't such a major hassle (although it's nicer to just go mobile when you can), but there are still lots of times where you can't, like on most airplane flights.