For the last few years (mostly due to financial restrictions), I've made do with onboard sound for my computers. It's free, it's usually adequate (especially now that most onboard solutions ship with optical outs), and for the budget conscious, we're happy to make do...
...HOWEVER: After using this sound card for just a couple of weeks, I have completely changed my tune (so to speak)! The quality of sound produced by this card isn't just good for computer sound, it's good, full stop! I felt guilty for about 2 days after shelling out about £135 on this, and that guilt alleviated the moment I heard it in operation. It's truly that good.
I should qualify my hyperbole by explaining a few things. First of all, I consider myself a bit of an audiophile. I'm not entirely a nutcase when it comes to sound, but I would certainly consider myself someone with a more discerning ear than the average user. Secondly, I was looking for a sound card that would give me two things in particular: excellent stereo sound, and excellent headphone usage. This sound card has dedicated hardware designed for headphones, and one can tell. It is simply the best headphone sound I've ever come across. Admittedly, if you purchased a top-end amplifier, some sound engineer somewhere will probably claim it is better, but for the money and its intended use you aren't going to beat this sound card for headphone usage. This sound card destroys the 'competition'.
When not using headphones, my sound card is plugged into a dedicated amplifier with good quality separate speakers. Again, in the domain of sound card solutions, this is the best sound I've ever heard produced from a computer, however I do wonder how noticeable the quality improvement would be if you aren't using at least decent speakers. From this point of view, I'd hesitate to suggest recommending this card to anyone who uses standard computer speakers (unless they were a heavy headphone user, of course).
One of the reasons why this sound card rinses the rest of the field for quality is the hardware employed. I won't go into the technical nitty gritty (google the card to find numerous reviews on this), but I think it suffices to say that any sound card that requires a dedicated power supply shows you that it's not your average card!
My only minor quibble is the same as the previous reviewer: the software isn't the best. It's a *bit* clunky, and changing between speakers and headphones is a little annoying, but even so, overall I forgive Asus.
This card does have an optical out, so will pass through surround sound streams, but I'm unable to comment on this as I prefer a stereo set up.
Overall, one of the best purchases I've ever made.