I'm sorry I must of not been so clear about my question...
Anyhow, I found out that there are no 128 -bit versions of this card, or better none from sapphire. After calling the merchant I had him give me the exact part number, and was able to find it on the sapphire help line and it is indeed a 256bit memory interface card so i bought it (113e). Plenty in stock btw if you live in Europe.
Meanwhile I don't have a good way of testing this, but it would still be nice to know how much the memory interface would affect mining (as in speed loss/gain based on 128 vr 256 bit interface).. i don't see my miner using much memory at all on the card thus I'm thinking it would not as most work is just gpu based but i do see on the forums that tweaking the speed of the memory does make differences so i'm not sure ><
thanks for all that replied btw.