That graphics card is just about minimum but the ram is no where near enough you need about 300MB just for windows to run in so your games have to load in and out of that 200MB spare ram and so it dont crash your games are also running on your virtual memory on the hard drive which is no where near fast enough to keep up with the game.
Not enough ram kills performance off all your components adding more ram than your aps need to run on, gains no performance. All my games running with windows takes up around 800- 1.6 GB of ram.