I was thinking about buying a $140.00 sound card but I'm not sure if I really need to spend that much if I'm just going to be hooking it up to my reciever via digital output cord. If I get a PC sound card and hook it up to my stereo reciever using the digital output cable(is that correct?), does the PC sound card effect the sound quality at all?

As long as the card can produce bit-perfect output then there is little need to worry. Many cheap cards can do this, but some require firmware and driver mods - search around a bit and you will no doubt find a cheap card that will output bit-perfect on it's digital output. One possible caveat is the quality of clocking - but it's a subtle (and intensely debated) issue, that expensive cards don't necessarily do any better at than cheaper cards.

The CMI8768 based card I mentioned in the other thread is capable of this with Dogbert's drivers. I got mine for £12.99 about 9 months ago.

With a digital connection, you shouldn't hear any difference between soundcards. Maybe "golden ear" audiophiles can hear the difference with a card that's not "bit perfect", but it will be a subtle difference.

Even with analog output, you won't hear much difference between a reasonably-good soundcard and a very-good soundcard... A good digital-to-analog converter is fairly easy to build. Noise is likely to be the "weak point". So, if you don't hear any (soundcard-generated) noise, you probably won't hear any improvement with a "better" card.

The only time I'd be looking for a high-end soundcard would be for (analog) input/recording... It is more difficult to build a good, low-noise, analog-to-digital converter.

This should do the trick:

http://www.lynxstudio.com/product_detail.asp?i=12