Do you mean that you get no video or that the graphics just plain suck? If the graphics just suck then it's the game. It's pretty old and having a newer and more powerful video card won't make it look awesome...
The graphics suck because the graphics were made for the original Playstation way back when; at least ten years ago.......
Last time I've checked, they haven't made FFXII for the PC...... yet. If you're talking about FFXI, the graphics are in par with the likes of Everquest II......