GamePC looks at Windows XP for AMD64
GamePC has a good first look the AMD64 version of Windows XP that's worth a read for anyone wondering why the operating system is so critical to the Athlon 64's success. The article raises an interesting point about the need for 64-bit drivers and whether Intel will cooperate:
What will be very interesting is if we see Intel branded products, such as network adapters and RAID controllers, being updated with AMD64 compatible drivers. After all, Intel products are quite vital to the workstation and server markets, even if they are just third-party add-in cards which are being used with AMD Opteron platforms. We threw a fairly standard Intel EtherExpress 10/100 NIC on our Opteron / Windows 64 test platform, and it did not have compatible drivers available by default. Keep in mind, this same NIC has native 32-bit Windows XP drivers.
A lack of AMD64 drivers for Intel-branded products certainly won't sink the Athlon 64, but Windows XP for AMD64's dependence on 64-bit drivers could be the platform's biggest weakness. It would surely enrage the enthusiast community, but it's entirely possible that more traditional 32-bit drivers will be updated more frequently and quickly than their AMD64-compatible counterparts.
It's also important to note that the GamePC article focuses on a recently release pre-beta version of Windows XP for AMD64. Pre-betas are a long way off from release candidates and gold masters, so it's probably safe to say that the Athlon 64 will be riding 32-bit Windows for a while.