Help me find a laptop under 800$ (Incl. of taxes) that meets my requirements?

I need a laptop for my studies at USC, California for MS Computer Science Course. Heard the tax on electronics goods is quite high in California. My budget is 800 $ inclusive of taxes. I guess that’s 700–730 $ without taxes, not sure of that.

My requirements are:

Intel Core i processor (i3 or i5)
4GB DDR3 RAM
320/500 GB Hard Disk
Nvidia or ATI graphics (512 or 1 GB)
Battery life of atleast 2.5 hours
14” or 15.6” HD Display
Good build quality (Shouldn’t feel cheap/plasticky)

The looks, weight of the notebook are not that important to me but the build quality must be good.

Thanks !