You can upgrade the ram and HDD in just about any netbook... the question is how willing you are to dig into the bowels of your machine in order to do it.
I would look into one that can do more than 4GB of ram (Atoms are great little CPUs, but that max of 2GB of memory really is annoying).
Acer makes a Celeron and Pentium based netbook for $350 or $380 respectively. Both come with a 500GB HDD, and 4GB of ram installed, which is a pretty good deal. Upgrade to Win8 Pro in October for $40 and you will even have a real OS on it.
The down side to having a 'real' cpu instead of an Atom or Fusion processor is that you only get 4-5 hours on the stock battery, compared to the 6-9 hours on other platforms. They do however make larger batteries for the ~$60 which would get that time back up in exchange for a little weight.
Also, the HDDs in these things are SLOW (a problem in all netbooks), so consider an SSD or hybrid drive to upgrade to down the line.
All that said; look for an ASUS eeePC netbook. Much better build quality, screens, web cameras, etc. But you pay for it by getting stuck with a much slower CPU, and less memory.
I personally own both brands. My Acer is ~2-3 years old, and is kicking pretty well with win8 on it. It has been extremely durable and survived many drops, kicks, being sat on, and generally tossed about. It never looked 'nice' but it was $280 back then and works just as well now as it did then (with the exception of battery life which is much better under win8)
My ASUS on the other hand has the same system specs, but is a convertable tablet (perfect for win8!). It is clearly built more rugged, it looks nicer, the screen is brighter (sadly the touch overlay looks like crap), the speakers are better, the web camera is better, and the whole thing is a bit bulkier, but it is still pretty nice.
Lastly; A netbook is a desktop accessory. I love both of them, and they have each served well for their roles of being cheap on-the-go laptops. But if I had to use it as my main computer every day I would go mad. If this is going to be your main PC then please look into a real laptop. They are less portable, and do not get the same epic battery life, but they have bigger screens, better keyboards, more upgrade options, and will be much easier to use in the long run.
I have a big laptop that is great and fast but i just want a little netbook that i can easily take in and out of class. I was looking at the Asus Eee PC 1015px pu17, but i cant find it anywhere online that they sell it? any help?
That is an older model which is discontinued, you may be able to find one used on ebay or something, but otherwise you will be out of luck. Trust me when I say that the minimum CPU you want in an ATOM 2600. The older 400 and 500 series simply suck.