Since Windows Vista(so 7 and 8) most sound work is handled by software anyway. OpenAL and ASIO can still be hardware accelerated, but need each program to be able to take advantage of it. For instance, you can get a plugin for many music players that WILL use hardware acceleration and depending on the card, can sound very good.
Now here is the interesting part. Modern CPU's have WAY more then enough power to get the job done when it comes to sound, but dedicated cards tend to have better quality parts. This applies mostly for analog output as digital will reply on your amp to do the conversion.
Short answer would be depending on your tastes, but it is important to know that software based cards are going to be the future(not good for some users, but most will not notice the difference).
I personally have an X-fi titanium and it works very good and sound great to me. I use hardware plugins when I can.