As long as my basic math skills are not called into question I am good. The long and the short is while I would like the 5870m to have 256bit bus for reasons stated. It does not matter. It is what it is. But further at least in my recent research and thoughts. The predetermined idea that 256bit is somehow better than 128bit is bunk. Many like to say the bus is somehow critical, almost magical? It is not and the 5870 basically proves it. The bus is just a means to an end same as clocks are. I think a lot of people that I have read need to rethink their common sense. And these are not people on this site per se.
edit: I forgot the memory amount. I would liken that to the loading/unloading zones where information is loaded onto and unloaded from the vehicles at each end of the highway.