I have an ECS Desknote 929 which is a good cheap machine. Now they don't come with a battery(well, an external one is offored) but if yon don't think you'd need one too much, they are a great system. I've had very few problems out of mine, and they are easy to upgrade seeing as they use standard DDR and SocketA processors.
Don't worry, it's not that light of a purple in person
You might want something with a battery, I donno, but I think you'd be happy with this if you simply need something you can carry around from place to place. I know I'm pleased with mine. Oh, and mine only cost me about $600 for an XP2000, 256M RAM, and a 20G HD