hd 7770 is an ok gfx card it will do medium-high settings on most any game and max most older 1s at 1920/1080 giving 60 fps.
as for the sound.
a basic audioligy 2 is a good basic sound card that will give just a little more umf. but will be a lot clearer due to better shielding
asus xonar d2 is a great card for the money and hard to beat at any price point unless you spend a rediculous amount of money.
i have a basic xfi sound balster and its perfectly adequate. gives true 5.1 and with games that use spacial audio like bf3 and cod you can tell if sum1 is creeping up on you being or behind to the left or right and so on.
again any of these will give less audio interference form the motherboard as they are separate and shielded.
So you think buying the SoundBlaster X-fi audio titanium HD isn't worth paying $160 for ? and how much are those sound cards you mentioned ? like anus xonar d2 ?
and for playing HD video 1080 like playboy videos, is the current card I have adequate ?