That ASUS K53U E-350 APU will not have an option to upgrade it's graphics.
The HD 6310 is more of a home theater graphics card than a gaming graphics card.
It should do 'OK' though on some older games.
The Staples $350 price is a good value though. It's $400 on some sites and I saw one for $470 on Amazon.
It's an older model - the current K53Us have the E-450 / Radeon HD 6320 combo but not worth the extra cost IMO.