Don't get confused after you have finalized something 
7050/7100 is better than g31 gfx performance & feature wise.
But intel g31 has more stability than 7050/7100.
But AMD 780G is far more better than both of the above gpus.
Don't even think of Athlon 64 X2 5200+.
Phenom X2 550 is far more better than X2 7850. It gives performance as close to Intel
e8400.
Gigabyte mobos has better power saving techs than any other mobos. So your power bills will be low.
So Stick with Phenom X2 550 & Gigabyte GA-MA78GM-US2H. It can easily handle your HTPC need & you will be able to spend some really good time with gaming on 780G.
7050/7100 is better than g31 gfx performance & feature wise.
But intel g31 has more stability than 7050/7100.
But AMD 780G is far more better than both of the above gpus.
Don't even think of Athlon 64 X2 5200+.
Phenom X2 550 is far more better than X2 7850. It gives performance as close to Intel
e8400.
Gigabyte mobos has better power saving techs than any other mobos. So your power bills will be low.
So Stick with Phenom X2 550 & Gigabyte GA-MA78GM-US2H. It can easily handle your HTPC need & you will be able to spend some really good time with gaming on 780G.