Um...That's an AGP graphics card.
DDR3 is coming out I think Q4 of this year, although I'm not 100% sure. But for now, it's not worth buying yet. For the graphic card, I would suggest either the 7900GS or X1950XT. You can get a 7900GS for as low as $150/$130 MIR, and the much more powerful X1950XT for as low as $190/$170 MIR.