If all you are going to be using it for is note taking, really anything will do. The top thing is the keyboard and how it fits in your hands. I would go to a Best Buy or other electronics store around you, test out all the netbooks until you find one with a keyboard you like, and then go online and find it cheaper.
I use a netbook for school and I love it. I highly recommend picking up OneNote, and then using it in conjunction with Dropbox (Create notebooks within your onenote folder). It has made school so much easier for me, it is very easy to stay organized.