I think these days most people use their video card as a sound card because monitors/displays generally have audio out as well.
But yeah. I remember having endless problems getting one of the Splinter Cells to run (I want to say Pandora Tomorrow?). After literally weeks of googling and discussing the issue on forums with others with the same problem, we found out that it had issues with the onboard sound for certain motherboards. Went out to Best Buy, bought the cheapest soundblaster they had, and no problems.
Splinter Cell 1 was the first game I got when I built one of my computers, and I went out and bought a surround sound set up just for it. Totally worth it. It blew my mind after dealing with chintzy desktop 2.0 setups and onboard speakers before that my whole life.