"The second reason I was thinking about getting a new card is that I can barely hear anyone with the in-game vox but have zero problems with my squad on Ventrilo. Not sure if this is a specific sound card issue or a game issue."
I'd check your mic levels in game first.
As far as getting vox through headsets and the rest of the sound through speakers, I have no clue if that is even possible. I doubt that it is possible with a single card setup.
I do run a simple splitter so I can do both headset or speakers. Each has a volume control giving me at least some options.