If you have digital optical or coax output from computer sure or just use a 1/8 phone cable to an RCA (red and white) into your receivers inputs but you won't have 5.1 and the best you could do it Pro logic.
HDMI cables can carry audio and video however, I doubt that the audio signal is transmitted through your video card via HDMI as that is what you sound card is for. Order the 1/8" to RCA cable from Monoprice and be done with it. You will never get Dolby digital sound unless your computer can decode and output it.