Moving away from X86 is bit of a chicken and egg scenario. Consumers don"t want the hardware unless the software is there to support it, and software guys won"t start developing software until there is available hardware on the market to back them up. Of the companies who have taken on the challenge of moving to 64-bit thus far (Intel, Sun, and Alpha), all have all been limited case scenarios. The companies have developed 64-bit processors specifically for usage in servers and high-end workstations, where the limited hardware and software that is compatible with their processors isn"t much of an issue, as they are looking at a very targeted user base.
AMD"s move to 64-bit processing is much more challenging, as they are targeting home users, gamers, and everyday business folks. In these markets, the amount of software, drivers, and subsequent headaches rises by leaps and bounds. AMD"s goal is to succeed where all of its competitors have failed, and succeeding in this goal not only requires flawless execution of the 64-bit hardware, but cooperation from some of the biggest names in the industry as well. There"s little doubt that the key player in this equation is Microsoft, whose release of Windows XP for AMD64 will be the litmus test to see if the world is ready to accept AMD"s take on 64-bit computing, or if the platform will be headed for obscurity.
Both AMD and its software partners agree that a true 64-bit operating for AMD64 processors is a necessity for the platform to be a success. There are variants of FreeBSD and Linux out there which already support the needed X86-64 extensions, most agree for that the platform to be taken seriously by the mass markets, a 64-bit variant of Windows is needed to take advantage of the Opteron/Athlon 64"s processor architecture.