Ubuntu seems to have recently developed a problem with choppy and stuttering audio when playing audio and video media. I don't recall this problem occurring when 12.04 was first installed but over the last few weeks as I've been trying to get multi-monitor desktops working, it became a major annoyance which remained even after disabling the multi-monitor desktops.

One solution is adding the following line to /etc/modprobe.d/alsa-base.conf:

options snd-hda-intel model=generic

Thanks to this thread for a solution. While the solution resolved the issue, it resulted in limited audio functionality on a Dell XPS 8300 a bit more research resulted in a better solution:

options snd-hda-intel model=dell

Since making this change the chop/stutter is completely gone and everything checked so far indicates that all of the ports and capabilities of the audio system are function.