http://www.rjtech.com/ has build-your-own base laptops in various sizes. Several OEMs that build for Dell, HP, Compaq et. al. are now selling barebones kits. If you shop for price on things like CPUs, RAM and hard drives, you can save several hundred dollars over the cost of a branded, retail laptop.
As much of a bad rap as Dell gets, I rather like their laptops. They are OEM/OED from companies like Compal and Wistron, they don't actually build any themselves, I don't think.
Even though their support has shifted about 80% to Asia, they are still very easy to work with. No arguments, for the most part, getting warranty repair service after a quick, by-the-book troubleshooting set. It helps a LOT if you've already figured out what the problem is.
Most of all I like their "Comlplete Care" plan. It's not cheap, and not a good deal on $600 PCs, but if your dropping two grand on a new laptop, it looks a lot better. Complete Care is an accident plan. Basically a warranty for you screwing up the PC. Provided it doesn't have a bullet hole in it, they'll replace stuff as though it were defective. Could come in very handy for a high mileage, fragile piece of hardware. Crack one LCD and the plan has just paid for itself.
Definitely get a widescreen, especially if video is a primary concern. Unless you have a real aversion to high res screens, get at least WSXGA+ (1680x1050) resolution. I got that and I regret not going with WUXGA (1920x1200) now.
The big 17s look nice, but are too large to use on an airplane if you're not in first class. Heavy mothers, too. The 15.4" is a good compromise. Anything smaller and you're down in lousy resolution range WXGA (1280x800). The little 12"s sure are easy to move around with though.
Right now I'm using a Dell Latitude D800. With the main battery and the optical drive bay holding a second battery, I can get about 7 hours of life if I'm not doing anything to strenuous. For use on a plane, you'll want the second battery and run the movie from a hard drive image. Optical drives are hell on battery life, and that bay is better served with 70% more juice in it.
If you decide to go with a Dell, definitely set yourself up in one of the Business sections, and not home/home office. For some odd reason, "home" users can't buy Latitude laptops. Having several Inspirons run through my fingers over the years, I can say assuredly that you want a Latitude if you plan to do anything interesting in your travels.
As for the BYOs, they are pretty new, and I have no direct experience with them. A lot of the names you've never heard of have been making major name laptops for years.
I'd highly reccomend you not go the Best Buy/CompUSA/Circuit City route. I wouldn't own another Compaq or HP at gunpoint. Sonys are overpriced and the company annoying.
For right now, Intel's Centrino/Pentium M/Core precessors are the way to go. AMD is making strides, but they aren't there yet. With the release of the new series of CPUs, the older models will be getting less expensive here real soon.