ultraportables are always a headache to choose...have to compromise between performance and weight. In the end, I went for the Acer Travelmate 3000 series with 1.73 GHz processor, 2 GB of RAM, 12.1" widescreen and a 60 GB hard drive. It weighs 1.3 kg (3 pounds).
The disadvantage is that the optical disk drive is external but that helps to keep it light, so I don't mind. As for the hard disk, I always save my data in a pocket external hard disk (80GB) anyway so the hard disk capacity on the machine does not matter much to me.