SAN JOSE, Calif. —  Apple Inc. (AAPL) is urging some iPod and iTunes users to hold off on upgrading computers to Windows Vista, warning that the iTunes music software may not work well with the new operating system from rival Microsoft Corp. (MSFT)

Apple said iTunes may work with many Vista computers, but the company knows of some compatibility problems and recommends that users wait until it resolves the issues with an iTunes update in the next few weeks, the company said in a statement provided Friday by spokesman Derick Mains.

The iTunes software is key to synching music on computers with iPod portable players.

• Click here for FOXNews.com's Personal Technology Center.

Microsoft launched Vista, its first major overhaul of Windows in five years, on Tuesday.

Though Microsoft and Apple are partners in some cases — iTunes works with Windows PCs and Microsoft Office has a version for Macs — the two are also entrenched rivals. With Vista's launch, Apple ramped up its ad campaign attacks against Windows.

According to a notice posted on Apple's Web site, compatibility problems include the inability to play music or video purchased from the online iTunes store, difficulties synchronizing contacts and calendars and possible failures of iPods plugged into a Vista computer.

Apple also outlined precautionary steps users could take to try to minimize any problems should they upgrade to Vista now.

Adam Anderson, a spokesman for Microsoft's Windows division, said the company did not believe iTunes users "should stop using Vista for these reasons."

The company said it is working with a long list of partners, including Apple, to make sure their software is compatible with Vista.

When the new operating system launched, Microsoft claimed more than 5,000 hardware and software products were already Vista-compatible.

The company has a dedicated team working with Apple on getting iTunes running smoothly on Vista, and it will keep at it "until they have the program running to the quality level they're shooting for," Anderson said.

Apple has sold more than 90 million iPods since the product was launched in October 2001.