I have had and used over the years, SB16, SBPro, SBlive, Turtle Beach Santa Cruz and Turtle Beach Montego, and of late, Auzentech Prelude, an X-FI gamer.
4-5 years ago I would have sworn, and have in fact argued on this very forum that no onboard sound would ever match a decent sound card.
But..........................
I just gave away the last sound cards I had, the X-FI and the Auzentech.
After the last 2 motherboards I have had, a DFI Lanparty, and the Gigabyte board I am using now, I could tell no big difference in sound quality, and just decided that there really isn't any need to bother with a Sound Card anymore.
I am not audiophile by any means, but I do like my music load and clear, and I have no problem with the new onboard modules delivering.