A 780G is good for a budget gamer build and not just an HTPC.
The only problem with AMD right now is that the B3 Phenom lags slightly behind Intel high end CPU's, but they do quite well against low end and older mainstream Core 2's in the same price range. Just take a look at Tom's new CPU charts.
I can't wait for the AM3 replacement for the 780G with the newer SB750 southbridge and DDR3. IMHO, it's always good to have an IGP on the motherboard for an extra monitor or an emergency replacement.
Just for fun, I removed the 3870x2 and played LOTRO for a bit with the 780G's IGP, and it wasn't that bad graphics wise (though when I tried Oblivion, forget about it!). If I'd not gotten a high end card earlier in the year, I would have gone hybrid Crossfire with a 3450.
So, I have to say that my favorite board right now is the Gigabyte 780G. When I do upgrade next, it will go into an HTPC, but it's decent for gaming right now.