My wife and I have matching ASUS 900A ($299.00 at Best Buy last fall) netbooks, and they work quite well. We run Ubuntu Linux 8.10 Intrepid; no idea if Windows does well on these machines.
If you get one of these with 1GB of RAM, spend $32.00 (shipped) on a 2GB upgrade from crucial.com It makes a big difference if you can minimize or eliminate disk swapping since the MLC Flash drives in these things are slow.
Speaking of flash drives, I replaced the tiny 4GB unit in mine with a 64GB MLC drive. ($115.00 at the time, but prices fluctuate all over the place).
They’re good little machines. My wife prefers her work-supplied MacBook, but that’s mainly a screen size issue. I use mine almost exclusively, and we also have a late model 20″ iMac and an older 12″ G4 iBook to choose from.
I laugh when I see reviews that say netbooks are only good for light surfing, email, etc. I use mine for everything but video editing and conversion, and I’m a programmer/tech guy. If I have to type a lot of stuff, I use an Apple Bluetooth keyboard, though–these little chicklet keys can slow you down.