I have purchased, used and broken about 65 laptops thus far in my career as an engineer. I would buy new ones and shuffle the old ones throughout the labs.
Compaq (and DEC, both before and after being bought by Compaq) = Sucky. HP = worse still. Toshiba = fair, just pray nothing goes wrong because their support is terrible. IBM = fair. Mac = fair (they're pretty, but slow and service and support are abismal).
Dell is by far the best. Most options, best support, best website and best price (especially when you factor in what you get which is quality). Spend the extra $100 (depends on model) for the 3 year onsite service. You break it, they come to you and fix it. I once inadvertently flung my laptop out of a convertible (didn't realize the bag was unzipped). Catapulted that sucker across the parking lot - SMASH. I called. They came. They fixed.
