In addition, Microsoft has engaged in talks to secure licenses to sell digital content for the device, the executives said.
It is unclear if the company intends to augment its existing online music service, MSN Music, or build one.
Sally Julien of Edelman, one of Microsoft's public relations firms, declined to comment.
Until now, Microsoft has stayed out of the digital music player market while licensing its Windows Media Player technology to Creative Technology Ltd., iRiver Inc., Samsung, and others.
But those companies have struggled to compete with Apple Computer Inc.'s line of iPods, which hold an 80 percent share of the market partly because of their seamless integration with the iTunes Music Store.
The stakes for Microsoft extend beyond the online music market, said Phil Leigh, an analyst with Inside Digital Media.
``It's becoming increasingly evident that video is migrating to the Internet, and Apple is getting a lead there as well."