My newest build also featured ALC 889 onboard and i agree it performed pretty much like you're describing.
It's ok and a marked improvement over previous generations of onboard but my old Audigy 2 on my 8yr old build sounds better.
I wasn't satisified with my new rigs onboard and purchased a Win 7 supported soundcard.
Couldn't be happier you can spend alot or somewhere in the $60 range for a decent card.
Asus,Auzentech,and Omega are worth looking into.
I bought an Auzentech Forte for my main rig it's a good all around performer and
is priced in the middle range of what decent cards cost.