Is it an s-video
connection you want? Those are a rare feature integrated into a motherboard, and are usually used for video connections rather than sound. Is it just a 1/8" (3.5mm) headphone plug you're after? Those are common, but I don't think they're digital. There's also the option of an AV connector (commonly the red, yellow,and white cable trio like one would use to plug a console into a TV). Again, rare, and usually for video only.
The Asus M2A-VM HDMI
has an integrated DVI connection running off of an ATI Express 1250 chip, and features HD audio, so it's pretty close to what you wanted.
Alternately, Abit's NF-M2
has a comparable feature set, but its graphics are fed by a GeForce 6150 northbridge, and it features S/PDIF in/out as well as a DVI connection. Both motherboards have 4 SATA ports and 2 PCI slots.
Asus A8N32-SLI - AMD X2 4200+ @ 2.7GHz - 2 x 1GB Corsair PC-3500LL @ 266MHz, 3-3-3-6 - SLI 7800GTs @ 505/1206 - Corsair HX620 PSU - Cooler Master RC-690
The two great evils of system tuning: YMMV and IIRC.