Welcome aboard.
Check the screen door. I thinks it's a little loose.
There is a difference between video cards. To make it simple, the more money the better. I have an ATI Mobility Radeon HD 6370 with 256mb dedicated video RAM. It is a mid level card and I can run the game at full settings without any problem. My old computer had an onboard card with shared RAM and I had to have the settings set low. There are others on this forum that are able to give much more information on different cards.
More RAM also helps the game run smoother.