correct you need to install Media Center from App store. There is new a new unofficial installer for MB that seems to work, I now have all my meta-data and images back, but some of the plug-ins still have issues.
I upgraded in place and Media browser will load and navigate and play anything but all metadata, folder and backdrop images are gone. The service will also not start and run. I'm now testing XBMC that has not an issue yet, Just not sure I can get it tweaked to function the way I had MB setup.
anti-virus is now called Windows Defender. Right click on the background in the Metro interface, at the bottom of screen is a button to bring up a list of all apps. I like it better than the old start menu.
Look carefully, there will be two kinds of Tablets and two versions of Windows 8. Arm type tablets will use Windows 8 RT and regular x86 CPU based tablets will Run Windows 8 Pro and can do anything your desktop can. The MS Surface is currently the RT version with plans to release an Intel version soon.I plan to wait for a Windows 8 Pro based Tablet.
HP has posted notes in their Windows upgrade information that states existing TouchScreens don't have full Windows 8 functionality, to get that requires a purchase of a new designed for Windows 8 system they will be releasing. Something about existing screens can only do two points. Since I was upgrading a desktop without Touch I didn't pay attention to the details.
a lot of WIN 8 is for big corporations who have constant issues with Micosoft Apps playing well with Smart Phones and Tablets. Expect hardware designed for Win 8 corporate user to be releasing over the next several months. Here's one Tablet/Notebook hybrid