I think different countries and languages can affect the way viruses work on machines. I looked at blasters source code and it had abunch of differnet languages in its code, i think it was shellcode for each version im not sure. It had numerous versions of japanese, chinese, russian, american, and more and then for each version of windows, win 2k, xp, me, and then for releases, like sp1 and sp2. I dont know how the releases would affect the way a virus could work on it or not unless they patched it and theres another way to exploit it with the patch.