Here is my HTPC. I used to run a Sapphire HD 7750 Low profile card in my HTPC, however it took forever to load movies streamed through netflix and the sound quality was terrible. I won the Gigabyte HD 7850 in a poker game(my friend couldn't cover the buy in so he put up his card as collateral). I might install Battlefield 3 to see what this little guy can do now seeing how this computer is connected to my 46" Sony Bravia tv. Mainly this will be used to stream movies and blu ray playback. The WD Green 1.5TB hdd was not being used, so I decided to throw it in for the hell of it.
EDIT: Did some benchmarking using Battlefield 3 MP. In 64 man conquest assault with settings set to Ultra in Operation Firestorm I was averaging 49.8fps with a min of 37fps and a max of 81fps. In 28 man Gun Master with setting set to Ultra in Scrapmetal and Donya Fortress I was averaging 51.9fps with a min of 40fps and a max of 60fps. Not bad at all for a Gigabyte HD 7850 2GB card at stock settings.