Agree with little ant on the graphics drivers installation. Hardware needs drivers to communicate with the overall system. since this is a standard model and even if you have changed/ upgraded rram or hdd please stick to your accompanied OS discs for installation. unlike DIY PCs the disc will also initiate graphics drivers installation after OS installation. Uninstalling graphics drivers is definitely not the solution. Try
here to update your graphics drivers. Your notebook model seems a little old and have you checked the system requirements on the games you played on your lappie? Is it like you have been playing it and wake up the next morning to find this problem with your computer or that all games you just get just cannot be played on your comp? Ram and processor may be an issue but it will be wiser to work on the graphics first and game vs hardware compatibility issue.