Microsoft believes nearly all major apps that can be found in Apple's iTunes store will also be available on Windows 8 by the fall, but it expects one glaring hole to remain.

"You shouldn't expect an iTunes app on Windows 8 any time soon," said Tami Reller, chief financial officer of Microsoft's (MSFT) Windows division. "ITunes is in high demand. The welcome mat has been laid out. It's not for lack of trying."

Windows 8 users can still get iTunes, but they can only use it in "desktop" mode -- the traditional PC interface that works far better with a keyboard and mouse than on a touchscreen. That means the growing number of Windows tablet users are getting a less-than-ideal iTunes experience -- or can't download iTunes at all, if they're using the Surface RT, which doesn't run non-Microsoft desktop software.

Users can also use Microsoft's Music app to play certain titles downloaded from iTunes, as long as they're not protected from digital rights management restrictions.

Apple's reluctance to make a Windows 8 app isn't surprising. Though the company has been willing to write software for Windows, including iTunes, Safari, and Quicktime, Apple (AAPL) is in a very different position in the PC market than it is in the tablet market. The Mac remains a niche PC, while the iPad is the single best-selling tablet by a wide margin. There's no reason for Apple to help make the Surface a better product.

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Meanwhile, the rest of the Windows app store is progressing nicely. Microsoft said it now has more than 60,000 apps available, and users have downloaded about 250 million of them. By the holiday season, the company believes the all of the most popular apps available for download in the iTunes App Store will be available for Windows 8.

"That's not just our goal, but it'll be realistic to achieve that," said Reller. "We're almost there."

Recent app additions include ESPN, Twitter, and MLB.TV. Microsoft has also made substantial improvements to its built-in apps, including Mail, Calendar, Bing and Video.

Microsoft does have a built-in Music app for Windows 8 that allows users to organize their music. Reller said that one day, Windows users may consider the Music app a viable alternative, but iTunes remains by far the most popular choice among music fans.