<3 Media". Even other people's formats—notably Apple favourites H.264 and AAC—are supported in the new OS, which comes with the newest Windows Media Player, version 12. But the biggest multimedia upgrade is Play To, a little WMP feature that eclipses all the rest.
Windows Media Player
Windows Media Player is never going to be the prettiest girl in school, but Windows 7 gives it a few upgrades that definitely makes it more useful.
File Compatibility For starters, Windows 7 now supports more types of media files, now including AAC in the audio department, and H.264, DivX and Xvid in video, with no third-party download needed. It also supports all of the formats it did before, including the earlier MPEG stuff and of course anything Microsoft had a hand in, not just WMA and WMV, but VC-1, too. This ability to read so much comes in handy in Play To, obsessively covered down below.
New WMP Interface Though we haven't dwelt on it, Windows Media Player's interface was subtly redesigned. Not only is there a neat pop-up mini music player for when you want to see what's playing but you're doing other stuff, there's also a new set of tabs on the right-hand side, including a Play, Burn and Sync. The differences are subtle at a glance, but for people who were heavy WMP11 users, this new version, WMP12, has much improved workflow. (Ars Technica did a nice detailed walkthrough of the new WMP interface, if you're interested.)
Speaking of "play," one of the most potentially groundbreaking features of Windows 7 is "Play To," the ability to send music, video and photos to any compatible devices on the network, without running any kind of proprietary software, and without any initial setup. Sending a song to a Sonos or a video to an Xbox is—theoretically—just a right-click away.
What devices work now? In our testing, we sent music to the Sonos and sent certain video files to the Xbox, though only when the Xbox was running the Windows Media Center Extender software. There are currently a number of other compliant "play to" products—such as the Roku SoundBridge—but since the spec itself isn't finalized yet, it's hard to just run a list. The DLNA itself will soon be announcing compatible products as they either come to market or receive the appropriate firmware update.