Once you use laptops extensively over a period of many years, and abuse the hell out of them (e.g. carry with you and actually WORK on them everywhere you go) there are essentially two choices (ok, 3..).
If you're a PC guy - the Thinkpads are the only choice, with the exception of the Toughbooks for anyone that is super insane. By far and away, nothing even comes close to the build quality and just generaly "always works" of the Thinkpads. I had a T40 last through over 3 years of use and absolute abuse (dropped down a flight of stairs, entire gallon of windshield washer fluid soaking it, many keyboards from spills, etc.) and is still going strong as a hand-me-down to an employee. The best part is dealing w/ IBM support is a dream. Notebooks will break, no matter how good they are. IBM you simply tell them "X broke" and they'll ship out a part no questions asked overnight. You also of course have the option of sending it in for repair - but generally it is not needed. On a T60 typing this right now, which has held up well for the 3 months I've had it. This seems a bit better than the T40/42/43's we have in the office, in terms of "solidness".
The other choice is Apple, if you need/want OS X. The powerbooks and Macbook Pro's are rather nice, and in my opinion come close to rivaling IBM/Lenovo's build quality in some cases. They definitely push the edge in terms of specs a bit more - the one thing I really miss on the T60 is DVI out, which is about my only complaint. The cool little 'extras' on the Apple's really do add up to a much better use experience, even though they seem petty and trivial at first glace (such as magenetic power connector, backlit keyboard, etc.)
So yes - at one point people told me the above about Thinkpads and I laughed at them "how can one laptop be so much better, plus it's expensive as hell!". Then I finally tried one out, and I absolutely will never use anything else unless Lenovo really drops the ball. Once you go IBM you never go back.
The worst of everything, imo is absolutey far and away Sony Vaio. They have a couple of select models which are okay, but in general they suck in both build quality and "engineering" (e.g. things don't quite work right). Definitely not made to stand up to the abuse of someone who actually uses a notebook as a portable computer. Have yet to see a Vaio last more than 6 months of heavy use until they were cheaper to replace than repair.
Hope it helps
-Phil