I've had IBM (now Lenovo) Thinkpads for something approaching 20 years. The early ones were bought by the august employer, but lately I've had to buy my own.
This one's a T43, with a titanium case that means even I can't break it. It's been excellent: came with Win XP Pro, been upgraded to Win 7, and I've fitted more memory in it (it has 1GB now).
It's light in weight, very reliable, and will do all those clever things one expects of a laptop.
The great plus is that it was absurdly cheap - I bought it "used", about six months old. I prefer to buy last year's wizzo model at a low price rather than pay serious money for something that's a few months more recent.