To the growing frustration and annoyance of Microsoft's management, Apple Computer's iPod is wildly popular among Microsoft's workers.

"About 80 percent of Microsoft employees who have a portable music player have an iPod," said one source, a high-level manager who asked to remain anonymous. "It's pretty staggering."

The source estimated 80 percent of Microsoft employees have a music player -- that translates to 16,000 iPod users among the 25,000 who work at or near Microsoft's corporate campus. "This irks the management team no end," said the source.

So popular is the iPod, executives are increasingly sending out memos frowning on its use.

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"These guys are really quite scared," said the source of Microsoft's management. "It shows how their backs are against the wall.... Even though it's Microsoft, no one is interested in what we have to offer, even our own employees."