Danny Beck, Microsoft Windows client senior product marketing manager, confirmed on Friday that servers running the company's Web site and MSN Search and Messenger applications had been migrated to the 64-bit version of Windows Server 2003.
"Our MSN search engine is actually built on several thousand systems running the x64 version of Windows," Beck said. In addition, "the entire Microsoft.com site has been migrated, and we serve 30 million unique visitors every day."
Beck said performance of the MSN Messenger servers has improved 10 times since they went 64-bit. The servers handle about 70 million instant-messenger users.
However, while Microsoft is keen to tout the server version's stability, the desktop version might have some issues, hardware makers have said. In addition, Greg Sullivan, a lead product manager in the company's Windows unit, told CNET News.com that the desktop version "" in terms of there being a market for it.
Advanced Micro Devices senior engineer Michael Apthorpe denied his company was disappointed with the release, but said he thought Microsoft had focused on key performance drivers rather than the "fluffy niceties" of operating system design.
While Microsoft has notably omitted 64-bit versions of some key programs--such as Outlook Express and Windows Media Player--in Windows XP x64, Apthorpe said that wasn't important.
"You only need to port what's necessary," he said. "If you've got a little graphic interface and it looks real pretty and it's 32-bit, that's fine--it'll run. But when you need the 32-bit addressing, the bigger data space, certainly port that into 64-bit."
Microsoft agreed, saying in a statement: "Some applications such as non-memory intensive applications, do not necessarily benefit customers by being 64-bit native."
The company unusually chose to include both 32- and 64-bit versions of Internet Explorer in the release. The statement clarified the reason behind the move, saying it was "simply because 32-bit ActiveX controls cannot be run in the 64-bit version" of IE.
AMD's 64-bit CPUs have been available in the desktop segment of the market for about 18 months.
Microsoft's Beck said most Microsoft applications such as the Office suite will not be available in 64-bit versions until the end of 2006, when the company's next-generation operating system, Longhorn, is due for release.
Renai LeMay of ZDNet Australia reported from Sydney.