AirPlay for Windows Media Center does exactly what you're thinking it does

This isn't the first time Windows has been invited to the AirPlay party, but Thomas Pleasance's AirPlay for Windows Media Center addin seems to already be one of the smoother combinations we've seen and it's still in beta. Unsurprisingly, it does what the name says, so after installing Apple's Bonjour service and the free client on your Media Center PC you should be able to stream video or pictures to it (there's no support for music yet) from an iPad or iPhone with a simple click. The Digital Lifestyle has already gotten a quick hands-on with the app and got it working seamlessly as seen above, check that out for more details or hit the source link to download the necessary software to make it all work.

ThomasPleasance.com