Not sure if I'm misunderstanding you, but doesn't the .7z extension mean that the roms are zipped with "7zip" and probably contain more than just one version of the rom in question? For example, Mario Kart 64 "unzipped" would have:
Mario Kart 64 (E)(v1.0)[!].z64
Mario Kart 64 (E)(v1.1)[!].z64
Mario Kart 64 (U)(v1.0)[!].z64
etc, etc, all contained in the same .7z zip.
My experience has been that those .7z files contain just about all versions of the rom.
Woah, I'm totally thrown for a loop here...never even heard of the compression method of "7zip" and .7z... I mean, there already is winzip, winrar, winace etc...why are people bothering using another different type of compression? Now I know why my roms weren't working. Hopefully this "7zip" program has a windows version. Thanks for the info.