Gigabyte GA-78LMT-USB 3 rev 4.0 will be perfect for your build.
other things are good. maybe you should think about your GPU , if you want a gpu for gaming then you'll need atleast HD 7750 or higher.
Thanks for this awesome advice of motherboard and about graphics i would say that i don't play heavy games evertime.. just around 3-4 hours a week like gta 4,far cry 3,NBA 2K12.....
Is this graphic card okay ? to play these games at good to high quality ?