I disagree with my fellow board members here about Dell.
Their business Latitude line is very solid. Their D510, D610 and D810 models are all built in a magnesium-alloy shell, including the LCD cover. This is just like the ThinkPads.
I have a D610 personally. I have not had problems with this machine yet in the 9 months I've had it. I've modded it so far by installing an Audigy 2 ZS PCMCIA card, 2x512MB DDR2-533 RAM and a new keyboard.
You can't find a laptop that does HyperThreading. Pentium Ms don't do that. However, this shouldn't matter - HT makes at most a 1-4% difference in performance, supposing the rest of your machine is weak. I speak from experience and benchmarking.
If you find a laptop that's lacking RAM, buy it. RAM can be upgraded at a fraction of the cost aftermarket by yourself. If you find yourself lacking hard drive space, don't buy it. Aftermarket hard drives will burn a hole through your wallet. Besides on some laptops, they're not hot-swappable, so upgrading would involve dismantling the machine.
Decide how much you want to carry the laptop. There are people who are crazy about 17" laptop models, until they start carrying it. It's a bucket of bricks. A 15" screen will suffice for most people. The XGA 15" would show you 1024x768 resolution, while an XSGA would give you a higher resolution.
I personally went with a 14.1" SXGA display which allows my laptop to be much smaller, yet it shows me a 1400x1050 resolution, superior to that of standard 15", 15.4" and 17" UXGA displays.
Check that your laptop has an available hot-swappable slot for a second battery. Usually you can swap your optical drive module for a second battery (no restart needed). Two batteries can be a lifesaver on a boring 7 hour trans-Atlantic flight.
