pc to av reciever help

[delboy13]

i am running a pc with vista on it and it has realtek hd audio. it has not got optical out or coax connection. i am moving in next couple of months and was going to buy an av reciever maybe onkyo 507. i wanted to know what do i need to do get digital sound to my av reciever. do i have to buy a new sound card
sound at the mo is onboard also added a pic of back of pc

thanks for any info

[chroma]

Asus Xonar DS PCI 7.1 Soundcard - Ebuyer (http://www.ebuyer.com/product/166836)

35 quid, a damned good soundcard wih decent drivers.

You could probably pick up a 2nd hand soundblaster for under a tenner though with SPDIF out though