Neowin was told that Microsoft is planning to release both Windows Media Player 10 and their MSN Music Store service on Thursday. The company's latest version of Media Player will feature a new design, online stores, support for new media formats and devices and improved library and jukebox support.
WMP10 will be included in Windows XP Media Center Edition 2005 which finalised (RTM) some time after SP2. Media Center 2005 is due to be released in October.
The MSN Music Store should compete with Apple iTunes, it will allow users to download music at $0.99 per song.
Source: Neowin (Check it out for some screenshots)