I own the NV7 and had a Live! before this, my speakers are BA635 2.1
For DVDs, games and CDs, the onboard sound beats the Live! or same.
For wav files and Mp3s, the onboard sound loses to the Live! Mp3 sounds flat and has no depth and cracks once in a blur moon. Wav files has no depth and sounds flat just like the Mp3.
Have not tried using a home theater 5.1 setup to try out the nForce APU DTS encoder coupled with the onboard sound yet, as my gf needed my PC to rush out her AutoCad drawings.
Not sure if about the CPU util, never noticed when I had the Live!
Note that I say onboard sound instead of nForce sound. This is because, nForce APU still needs a sound chip to interface it's data into 5.1 sound. eg cMedia or Realtek, thus the quality of the sound partly or largely lies with how the manufacturer of the motherboard implement the audio. You should try and ask the Asus nForce pple on how their sound is like.
But this is a very stable board. The drivers are great in the sense that the onboard sound, NIC, VGA (if applicable) AGP, IDE controllers, north, south bridge drivers are ROLLED into one driver.. unlike some 4in1s we know...