First idea: The files that stutter on Linux after you edit them, did you try
to play them in XP? Does it stutter there?

Second idea: If the files stutter in XP and it is an issue with
Ubuntu/Audacity, I'm guessing that maybe you'll need to tweak the kernel so
that it loads less modules. I'm not sure how to do it off the top of my head
but there are tutorials online that show you how to maximize the kernel for
sound and video editing.

Please let us know how you progress on this.

It may be trying to talk to the sound card. Check your setting under the
preferences and match it up with the windows version.

Actually, any files I open there won't play, whether I've edited them or not.
And, yes, they will play on Audacity in XP. Even the ones I've edited, so the
editing does work in Linux, it just won't play it back.
Thanks for the response.

In Audacity on Ubuntu, I can play a raw audio file, then edit it and save
it, then play the edited track. There's no problem with Audacity per se.
Your problem sounds to me like a configuration difficulty, probably with the
soundcard.

XP will skip rather than track if the CPU is busy with other tasks or is
slow. Check to see what else you have running at the same time.

Does your computer use pulseaudio? (It's the default.)

There is a long how-to in the Ubuntu Forums about pulseaudio. My approach was
to remove it...

Yeah, it uses pulsaudio. I'll check into that.