Actually, that is what bakerboy was referring to - your HDMI output cannot send sound to the TV because the sound is not connected to the video card - hence the "little white plug with 2 wires" - you'll need to figure out how to do this, but your instructions that came with the card should help in that respect.
And what I meant was that if you connect the TV to the PC using HDMI and *don't* have the speakers connected to the TV, does the TV play anything? That was to help narrow down the problem - is it the PC not putting out sound or is it the TV not send the input sound from the PC to the speakers. Clearly, this solution from the other thread you posted and bakerboy's reply (albeit very vague) indicate that the TV will not get any sound from the PC in HDMI regardless of whether the speakers are connected via TOSLINK or not - which makes sense, since you haven't connected your sound card to your video card.
BTW, this is all going on *inside* to computer - don't go looking at the back of the machine where you connect the HDMI cable at.