What the GP is talking about is Windows 7 Starter's 2GB RAM limit. You can stuff more RAM into a machine running Starter (which is most netbooks) but it will only actually use 2GB. To be able to use more than 2GB with your netbook you need to upgrade to Windows 7 Home Premium which is about $80, in addition to the cost to upgrade the RAM. This means the average $200 netbook ends up costing $400 to have a decent amount of RAM available.
I've seen very few netbooks that ship with Home Basic or Home Premium out of the box, most I've ever seen have Starter. Not only is the RAM limit a problem but it also gimps a lot of basic OS features like the ability to use multiple monitors, DVD playback, and fast user switching. Microsoft has put a lot of work into making sure the average netbook is just a crippled web terminal.