I'm running the laptop on battery power. I can hear a hiss during recording, I can during playback too (I said that there is no noise when I hear music/mp3s). I was able to remove a whole lot of noise because the sound card had a MIC boost. I still hear a hiss.
Example:
http://www.alldevs.com/media/noise.wav
Pardon the 1.5 MB download (didn't convert to mp3)
Example:
http://www.alldevs.com/media/noise.wav
Pardon the 1.5 MB download (didn't convert to mp3)