A separate sound card will gve you an incomparable sound quality, no matter your speaker setup.
The deal is i wouldn't buy the Fatal1ty (hypocresy any1? ) because, as far as i know, there are less games optimized fr the X-RAM than games optimized for PhysX. Given the PhysX games are like 15 or less, imagine the games optimized for X-RAM. Only ones on the top of my head are UT2004 and UT3.
I'd buy the Titanium.
I would spend the extra $15 on the Fatal1ty over the Titanium as a cosmetic upgrade. I've spent more on GPU backplates and the "X-Fi" light up on the Fatal1ty case looks cool.