is ddr3 graphic card works with ddr2 ram???

Your graphic card has a memory of her own like 256, 512 or 1G and recent graphic card uses DDR3 type for performance purposes. RAM in your motherboard are not related to your internal video card, unless it is a built-in video which take some from your RAM memory.

the graphic card has it's own dedicated memory, the new VGA now use DDR3 version, there is no problem to use it with your pc DDR2 RAM..

I am not too sure, if i am right the ddr3 memory is only for the graphic card only. Your pc will not make use of it. Modern day graphics card come with their own memory to reduce conflicts and to increase speed..so i suppose it is ok to buy a ddr3 Graphic card.. but i suggest you ask the shop owner first before purchasing though. With nvidia drivers being a little buggy there is chance of incompatibility.. but i am going to say if you can use than your ddr2 might pose as a bottleneck in your system.

By buying a VGA with DDR3 memory would be faster then DDR2 memory embedded, maybe this is your friend mean, although in the same series. AS GForce 9500GT, there are 2 models one with DDR2 and the others with DDR3. Not associated with your DDR2 memory RAM.