I worked for 2 years with a netbook as a main machine. A Samsung N250; I might have bumped up the RAM to 2GB.

I could carry it everywhere and it was fast enough for KDE, Arch Linux and web development.

I was also young enough not to have problem with the 11' screen.

I think the screen broke during an hackathon (I think it fell) and I just plugged it to an external screen and kept on working.