At work, so I'll just copy and paste something I typed up a few days ago in a different thread:
As far as the OS goes, I like Windows 8.1 on my HTPC and I run it without a start menu app. I think the metro interface is decent for a 10 foot interface, much easier to use from the couch than the start menu in XP was. I prefer the look and feel of XP and 7 for a desktop, but I like 8 for a HTPC quite a bit. If you want a start menu, Classic Shell is very good. I don't really use any Metro Apps, but, for example, the NetFlix app is easier for my extended family to use than the browser.
As for no DVD support in 8.1, this can be fixed by installing VLC (free) or any player that you would use to watch Blu-Rays.
I did have to get a discrete GPU when I installed Win8 because AMD decided to not make drivers for "legacy" chipsets, even though those chipsets were only a few years old.
BTW: I read someone that Windows 8 still comes with downgrade rights, so you can buy 8 and install 7, but if you buy 7 you can't install 8 in the future.