Re: Optical Digital Audio Out
Like everything, it all depends on your budget, your setup and your tastes.
You can find computer 5.1 setups for ~$150, including a decoder (received the SPDIF format, either optically or electrically). After that, sky is the limit. You can buy an receiver amplifier/decoder and speakers separately, price rises with quality (most of the time), all in one packs (usually lower quality) and so on. Depends on what type of setup you want and how much you're ready to pay.
Don't necessarily listen to people though, what is enough to you, may be perceived as "crap" by others...
As the universe is curved, there cannot be a straight answer...