A nice sound card would do your set-up alot of justice, gamer of not. like stated already on the 1905 a new card would be laid to waste, but a soundcard would take a load of work from the CPU giving more cycles to other things.
I just got a soundblaster X-Fi platinum and it has made a day/night difference in my gaming performance and just the simple fact that music and movies sound alot better.
either way Vital, keep us updated on what direction you decide to go in.
Good Luck