The company is selling its HDA X-Plosion 7.1 DTS connect card and you can buy this one today at Overclockers.co.uk for £88 including VAT here.
Trust me, I played with setting a computer on a surround amplifier and if you connect your PC with integrated sound or even high end X-FI card digitally all you can get is stereo signal. This is the case with both SPDIF out or Optical out. I confirmed this with a brother that happens to be a sound engineer. You won't be able to get even 5.1 or 7.1 without a card that supports Dolby Digital Live.
The X-Plosion 7.1 DTS should be able to do it and with some luck we might be able to tell you this first hand soon.
The company plans a new card with C-Media 8788 that will get even better. I think this card actually might replace the loss of Sound Storm that Nvidia killed so casually. µ