On the ASUS site it says AGP.
The DDR3 refers to the Memory thats in the Card - nothing to do with your Motherboard. It IS compatible.
AGP cards are getting harder to source, a 7950 would be a good choice, if you can find one.
The higher the model number - ie 7950, the better the performance, so a 7950 is a much better card than, say, a 7200