PC Magazine's annual survey of laptops showed the best three were Apple, Fujitsu, and Lenovo (IBM) in that order. The metrics were reliability, tech support, repairs, percent needing repair, and likelihood of recommending.
Toshiba is worth consideration, but only the Tecra and Portege line, skip the Satellites.
I disagree with Scott's IBM brand/pricing opinion, since they were bought by Lenovo a couple years ago I think there is no longer a premium for their systems.
Apple laptops are always worth considering because they're the only machines that can both be a Mac and a PC.
HP in case you're wondering is below average for tech support and repairs.
XP's was granted a "stay of execution" and MS will offer it until midyear 2008. I'd pick XP over Vista.
(Gratuitous plug - I sell the Macs and Lenovos)