While I use dedicated graphics myself, I have to say that the AMD Llano and Trinity chips have impressed me greatly.
I have built systems for friends and relatives who have been on tight budgets, and the performance offered has blown me away, I am fairly certain my next laptop will contain and AMD APU unless the new Haswell GT3 beats AMD's New Richland
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As for Gigabyte motherboards, they do offer incredible reliability, all brands are doing really well at the moment, my only gripe with Asus was their lack of windows 7 support at launch, especially with relatively new boards, but no-one manufacturer is completely flawless.
Enjoy building the AMD rig, do check for upcoming Richland APU's as they should offer a performance boost over the current generation.
Don't forget to back your system with a decent power supply
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and have fun.