I bought an HP Netbook Mini 210-1011 just over a year ago and have had great service from it. As with many of the early netbooks I found that I needed to upgrade the RAM to 2Gb and the OS from Win 7 Starter to Win 7 Home Premium to make it work speedily and to work with all my applications. It does have a long battery life (over 9 hours) with the extended battery that I have, it is nicely portable and has served me well.
That said if I was looking for a model today I would probably go with this Asus Transformer which on the face of it has all the advantages of a tablet when travelling and can be used with a keyboard for a semi-fixed installation at home. I have no experience with it. The other alternative I would consider is the IPad2.