Looks like you have the Intel D845BG motherboard. It definitely does not take DDR-400 ram. This is what you will need:
http://www.newegg.com/Product/Produc...82E16820145024
DDR-266 ram. I would buy two of these and replace the two older sticks on the motherboard.
Also, there is a very good chance that the videocard you're thinking about buying will not improve gaming performance at all. It's a piece of shit for gaming, there's no getting around it. If you do buy it, do not be surprised if games don't run any better than they currently do. The cheapest videocard you could buy that has a chance of improving gaming FPS is this:
http://www.newegg.com/Product/Produc...82E16814131070
And then again, depending on the game, it may not help out that much if the game is CPU limited. That's the chance you take if you're trying to turn chicken shit into chicken salad though!!