I strongly suggest getting a 14.1" ThinkPad T6x series laptop. I have had a T60 for almost two years now and it has worked great. The keyboard is just amazing compared to anything else out there. The TrackPoint (little red mouse pointer thing in the keyboard) is great when you get used to it. Unless you play games, you should get the integrated graphics (great battery life and easier to get working under Linux). The only bad thing about ThinkPads is that they don't run Mac OS X (legally/easily).

If you are on a budget, I recommend getting a slightly older model (slower processor) but with as much memory as you can get. I also recommend that you get a model with the one-year warranty instead of the three-year warranty, to save money. There are so many people selling ThinkPad parts and accessories that there is no reason to pay for a warranty that you will probably never use when you can replace anything that breaks yourself for less money. I just priced one at lenovo.com and it was less than $1,100.

BTW, I strongly considered buying a MacBook but I went and tried them at the Apple store and I found that the keyboard is really horrible for programming. Only Sony VAIO is worse. No dedicated home/end/pageup/pagedown on either?!?!