Windows x64 offers 32-bit compatibility on user software level. It does not support 16-bit software any more. In terms of changeover, this is a similar situation as it was in case of the 32-bit changeover. This situation is, however, better by one aspect: now, compatibility of a new operating system is highly extendable by means of virtualisation. Although the original purpose of virtualisation, of course, was not the extension of compatibility, it is still a very good, often the only possibility to do it.