Intel’s other guidelines for what separates a netbook from a fuller featured notebook? If it has a screen between 7 and 12 inches, for instance, along with a low price, it’s a netbook. Intel would also probably prefer it if all netbooks used Intel Atom or Celeron processors, but I think it’s safe to say that any cheap mini-laptop with a low power Intel, VIA, or even AMD processor can probably be considered a netbook. If it looks like a duck and all that.
Of course, there are still plenty of netbooks with 10 inch or smaller screens that are going for more than $400, but most Intel Atom based systems sell for under $500.