Consider a lenovo thinkpad if you really want a windows machine. I like the T series ones for size/performance ratio. My IBM T-41p has lasted many years, and it's fully field-serviceable by the end user. I had a fan go out (after 5 years of use) while I was TDY living in a billeting room with almost no tools, and replacing it took less than an hour. It has a socketed cpu, which I of course upgraded

The hard drive is removeable with just a few screws and you can buy an additional drive chassis for just a few bucks. Some people say that the quality has dropped since IBM sold the line to Lenovo, but I think the "thinkpad" line is still essentially the same with regards to design philosophy. They're rugged, focus on the most important features, and can generally be repaired or rebuilt with nothing but a screwdriver.
On the other hand, if I was going to buy a laptop today I'd get a macbook or the smaller macbook pro. Those things are well built and they have lots of great features. I'd run either boot camp and windows 7, or parallels/vmware and load up MS office because that's what I use at work.