Yes, only H and Q boards have got the needed connectors. P does not. When you want to use every game you will most likely need a dedicated card, for some simples ones onboard might be enough. But intel Linux drivers have been always slower than the Win drivers for games, so more interesting will be libva support - and i want to see vc1 too... When you look at the libva git log you will see h264+mpeg2 for sandy bridge already:
http://cgit.freedesktop.org/libva/log/
I did not test my i5-680 lately, if somebody has got one H5 board too much send it to me... But when i tested it vlc was not able to use DXVA2 correctly - libva was better, but i only tested hd samples.