I'm still using a Samsung XP 10" netbook as my main travelling computer. As ftorres noted these can run full MS Office perfectly happy, even Access and Project. I'm an IT project manager by trade and have hammered this with Word, Excel, Project, Powerpoint and some Access.
What's more it's perfectly happy driving my 23" monitor in 1920x1080, and attached keyboard and mouse, when I want to work at home in silence. (My desktop sounds like a 747 coming into land.)
I did upgrade the memory to 2 GB, and switched to a better battery pack - which gives me over 6 hours - but this has been an incredibly cheap solution for the power of the device.