The downside of netbooks is that there is weak processor power, and it is next to impossible to post process photos.
I've been in the market for 3 lb range netbook for a while now and looking at the 11 and 12 inch models for the slightly higher screen resolution. The higher end models (upper $400 to high $500's) include dual core processors and with Win 7 Home Premium 64 bit installed it's possible to do some degree of PP since some models can be upgraded 4 gigs of RAM. On the down side, a more powerful netbook chews up the battery power (~3 hrs on a 6 cell?) faster so there's a trade off.
AMD came out with the Athlon Neo X2 L335 (dual core) which I saw in an MSI and Lenovo. There's also a few models by other manufacturers that uses the Intel dual core. You can also upgrade the hard drive in netbooks to 7200 rpm if you prefer the extra speed over a 5400.

