As you might of heard Windows Media Center is not included by default in Windows any more. Microsoft have basically discontinued development of it unfortunately. However it will be sold as a paid for upgrade once Windows 8 is released. With the release preview you can enable it for free by completing the steps below: Swipe in from the right edge of the screen, and then tap Search. If you're using a mouse, point to the upper-right corner of the screen, and then click Search.) Enter add features in the search box, and then tap or click Add features to Windows 8. Tap or click I already have a product key. Enter this product key: MBFBV-W3DP2-2MVKN-PJCQD-KKTF7 and then click Next. Select the checkbox to accept the license terms and then click Add features. Your PC will restart and Windows Media Center will now be on your PC and the tile will be pinned to the Start screen. End Result: If you do have a dedicated Windows Media Center machine there is little point in upgrading to Windows 8, as you will find nothing new, and you will have to pay for the same Media Center you had in Windows 7.
Yup the only thing that will really change is that Media Player will loose the ability to playback DVD's. I'm guessing if you purchase the media center add on it will come with the ability to play DVD's (i would hope anyway). For our media center i'm sticking with Windows 7, no reason to upgrade it.