With that motherboard, you might as well overclock, as much as you can without gaining any temperature increases.
AS for the power, I'd go with something SeaSonic rebranded, mainly because I just love them so dearly.
I've heard a few OCZ flame-ups, but nothing huge.
Might be better suited with a ~550-600 Antec/Corsair/Seasonic/PC&C.. etc.
My opinions entirely.
Your HTPC is going to be a faster build than my main gaming rid... sad.
