thats "stutter" must be the pulseaudio issues which people are complaining about on ubuntuforums.org. even tho this is supposed to be an LTS release the developers released new untested stuff like pulseaudio knowning about the issues... can you try uninstalling pulseaudio and installing alsa... i am not sure how to do it, audio works fine for me. i was always worried since the early days of hardy about why ubuntu people are adding so much new unstable stuff for an LTS... maybe that is why they have an update release scheduled for june/july version 8.04.1 i guess gutsy was a super release.