Help a noobie!

More info please. Full specifications.

what is the difference of a 256bit 1gb memory and a 512bit 1gb memory? i'm just here to ask the "bit" because i just want to know if does really affect the performance of a card.  

feel free to correct me if im wrong anyone but im pretty sure its the size of the bus used.

memory ring bus or something or other.

bigger is better, am i not right.

For a single card solution, the higher the bus the better the performance, generally.

For a multi-card setup, the larger the bus, the lower the scaling efficiency, as the bus size will effect how saturated the PCI-lanes will be. Two 128 bit cards (like the 5770 for example) will be better bang for the buck with near 100% increase in performance with adding a second card. But, if you start with a higher performing card (like a 5850) and add a second one, there is far less than %100 increase (closer to 70% in this example) in performance, due mainly to saturation of the PCI lanes, from its larger bus.