This is a big issue now, with many PC producers providing partition recovery sections rather than discs. And the discs they permit us to make are not true OS discs.
If the upgrade path will require that I have a Vista disc, then I am going to uninstall W7 now and go back to Vista, because I know that I won't be able to afford a full version.
If the upgrade path will require that I have a Vista disc, then I am going to uninstall W7 now and go back to Vista, because I know that I won't be able to afford a full version.