Netbooks: I like Asus brand, personally, but I'm sure the other brands are ok too.
RAM: Depends on whether it's DDR2 or DDR3. DDR3 is effectively double what DDR2 is. So 2GB of DDR3= 4 GB DDR2.
Apart from that, it's a size preference. Smaller ones will be more portable, have slightly longer battery life and be a bit cheaper, but will not cool as efficiently and have terrible on-board sound. Larger ones will be... larger and have the opposite of those things.
And depending on your price range, you might just be better off getting a new full-sized laptop if your priorities lie more in speed and processing power over portability. From personal observations, the smaller netbook is handy, but a smaller display can seem cramped if you're used to a larger one.
If you want to post some links I can take a look and suggest one for you.