would like to ask the difference between my asus hd 4850 512mb gfx card with a sapphire hd 4850 1gb priced around rm200 found in lelong.com.... any ideas its quality difference?

one more question....still related to gfx.... lets say the gfx card have a dvi and hdmi port... my monitor supports dvi cable... what happens if i buy a dvi to hdmi adaptor.... will there be any difference to the quality of the picture?

thank you very much