I have a 10" ASUS Eee PC 1000 HE, which is amazing. Battery life is great (8h+) and it has everything you need (apart from an optical drive, but I didn't really miss that so far; didn't even see the need to hook it up to my PC's drive... which is certainly possible, though - the only thing I would want one for is to be able to watch DVDs/Blurays while traveling, so maybe I will get me an external drive eventually).
From what you say, Netbook is clearly the class of portable computer you want.
Pros: Inexpensive, small and highly portable, good battery life.
Cons: Weak CPU, no 3D gfx worth mentioning, not suitable for gaming.
What to look for especially:
- Battery Life (most important aspect, IMHO)
- Screen (10" is pretty small already, I wouldn't go lower than that; my ASUS has a 1024x600 native resolution, but an option to turn it to virtual 1024x768, which is *extremely* useful, since some program windows otherwise do not fit the screen and make it very hard to use them)
- Keyboard (you really have to see those in person to see if they suit you; my ASUS has a pretty good keyboard, which is easy to type with, considering the small size)
- maybe look for one with a modern Chipset (there have been some advances in this sector)
Bye
Thanee