Lenovo Thinkpad if you hate Apple and couldn't even stand using bootcamp to run Windows exclusively.
Dells are poorly built, both in fit and finish and components. Sony laptops are hit/miss, but I know a lot of people who love theirs. As for HP/Compaq and the rest of them, don't even bother. Remember: You'll be hauling this laptop around, so how much it weighs and how big it is actually matters.
wouldn't be a bad place to start looking for a windows based laptop. At least they understand that design matters. And yes, make sure to get XP Pro. It shouldn't matter, but it's been much more stable for me.