Yes if you've got a spare pci slot to put it in (3 slots is a bit tight) you would have to also disable the on-board graphic card via the bois settings.
Not being a game player myself, I'm not that up to date with what specs games need. But with a p11 processor then you might find that even with a new graphic cards will not recify the problems fully.
Also the memory would also effect how well a game will play.
sadly santa might have to make a emergencey earlier visit will a new computer or major up-grade?