it mentioned only palit 1gig ddr2 128 bit and the other is palit 256mb ddr3 128 bit.
the saleman inform me that palit 256mb ddr3 128 bit is more speed. is that correct ??
If this is ALL the salesman is telling you, then DO NOT buy from him. The model of the card is the most important aspect of the card.
I can inform you the 1 GB GDDR2 (it's GDDR, not DDR....they're quite different) card is a waste based on those figures. A GDDR2 / 128 bit card would never utilize the whole 1 GB of the GDDR2 RAM. The second card sounds like a more efficient pariing of RAM type, capacity and bit depth.
However, without knowing what model the card is (such as a 9600 GT or 7800 GTX) we cannot provide you with a sincere recommendation.