SIIG SoundWave 7.1

Firebat

Hello I signed up after reading some of the threads here and saw that everyone was really knowledgeable so I thought I would ask my question.

My problem is this: I just upgraded to a EVGA 750i board which has 7.1 mini plug surround sound. My old gigabyte board had a digital coax SPDIF plug that I used to hook into my stereo receiver. It worked great, 5.1. The problem is this board doesn't have that, so I went out to buy a pci sound card that did. I found a good one that I liked made by SIIG its a soundwave 7.1 pci. But it will only output SPDIF in two channels (and not all the time only when it feels like it). Even though previously I was doing 5.1. So I need your help to figure this out. Is it a driver issue? Why would the gigabyte board support this so well while my sound card can't.

new egg says its Hardware Decode is Dolby Digital EX, DTS-EX
and features:
Digital EX and DTS ES 6.1/7.1CH DVD audio formats
Supports the latest in 3D audio technologies, including Sensaura EAX v1 and v2, A3Dv1, & DirectSound

if anyone has any drivers that would work I would love you forver.
im running XP 64


edit: here is the product: http://www.siig.com/ViewProduct.aspx?pn=IC-710012
and here is the drivers they support (no x64): http://www.siig.com/Drivers.aspx?pn=IC-710012

Firebat

my motherboard also has a SPDIF optical out which was doing 2.1 as well maybe I could simulate 5.1 from that?