Firstly do you
really need the portability. If it's only going to get used in one place in the house, then a desktop will suffice, and be a lot cheaper for equivalent specs. If you want portability even within the house, then you'll want a wireless setup in the house - would add to your budget to add an access point if you dont have that already.
The other big factor is screen size. Smaller is more portable as less weight, but screen size can be important when increasingly sites add more and more content.
As for what we might recommend, do you have any sort of budget? Ah you just added that in your edit
