I'm thinking in buying a new laptop, probably Lenovo, the one I saw is an i3-3110M G500 with 2GB RAM (DDR3 1600), and integrated video, I'm thinking in buying additional 4GB, I was told that nowadays most laptop comes with 2 RAM slots and you can put different RAM sizes into the slots, is it right? If I buy an additional 4GB of RAM (I'll have total of 6GB RAM, 2 GB original + 4GB bought separate), will this work? This additional 4GB will be shared by video as well?