Yes. If you can run L4D2, then you can, seeing as they have almost the same spec. Portal 2 actually has relatively low requirements for today's standards. It almost ran on my old computer, which had an ATI Radeon 9800 pro, until it told me I needed Shader Model 3.0 :c
My graphics card isn't as good as yours and it runs fine, so you should be OK on that front. I have HD 6770 1gb.
Yes I really said an Intel graphics card.
