Windows 7: Cable for digital audio out for SB Audigy 2 card

I have a very old but very functional computer that I'd like to connect to my surround sound PC speakers. I currently have the computer connected to the speakers via the analog green, yellow and black cables, but my card states that it can support digital audio out, but I'm not sure what kind of cable to use for digital out. I've tried looking on here, but didn't find a solution, probably since my audio card is about 8 or so years old. It appears to be some sort of coaxial output on the card, but maybe not. I've attached pictures of my actual sound card, the far right port is the digital out. The sound card is SB Audigy 2 and my speakers are Altec Lansing ADA995 speakers, thanks in advance, I've been looking for a solution for a long time.

Dell used a custom Audigy 2ZS but it still is basically the same as the Retail version. According to the Creative (SoundBlaster) site it's a standard 1/8" (3.5mm) stereo plug. It is not "optical" (TOS) so you will need a compatible "digital" input on your surround amplifier for it to work. Probably the best thing is to continue using it the way you are now.