+1 on the Lenovo T61. Hell even an R60 would fit what you want. Those things are quick, built like tanks and just rock. I dropped mine on cement from 6 feet and all it did was scuff the shell. Also there's a drain system not many know about. If water is spilled on the keyboard it'll fall into little canals that'll lead it out the bottom away from important hardware. There's a hard drive monitor built in so when it detects the laptop falling it'll park the heads on the HD so nothing gets messed up. You can get one for less than 200 bucks now days and usually comes equippend with a core duo CPU which is plenty quick. Memory obviously upgradeable. I put Windows 7 on mine and it ran like a dream. The keyboard is the best laptop keyboard I've ever used and trackpoint is just awesome in every way once you get used to it. You won't be playing any new video games on it but anything else it's perfect.
Starting with the T60/R60 they started using a magnesium alloy honeycomb cage in the shell of the laptop in case of impact.