From what I've heard I would prefer AMD iGPU over Intel iGPU. However if you want the best GPU for HTPC grab a 7750.
Enough, I had more than one year running.PSU 80W is pretty low given the 55W cpu. I'm guessing that PSU is designed for low wattage cpu. I'd recommend lots of research into this, you may be better off using a 'mobile' low wattage intel cpu or a bigger PSU.