Have you tried playing any games with the HD4000 graphics or does your CPU not support it?
I am in process of building a HTPC and I would like to play some light gaming also...
I am looking at getting a gigabyte mini itx board to go with my I3 and just stick with the HD4000. Only game I really want to play is star craft 2 and some retro emulators.
I am going to have an Intel 530 in it