I personally don't see how this can be a good 'upgrade' or even sidegrade. if you are playing games, the g-card is the most important, you can always turn up the visual eye candy like AA/AF/detail level to suck out every ounce of power from g-card, downgrading the gcard only makes your game visually less attractive. CPU wise i3 21xx is quite enough may even be little faster in some games compare to x6 although at 4ghz, that's not going to bottleneck you much at all.
In short, I think OP's gaming experience is degraded by this particular upgrade.