I'm experiencing Video Tearing while in Boxee in Intrepid.
The system is a:
PentiumD 2.8 Dual Core
1 gig of RAM
ATI x1300 256mb
Compiz is disabled and vsync is enabled. Drivers updated through the Restricted Drivers GUI to the latest and "greatest."
The tearing is actually system wide (Well, in VLC at the least), but I don't know where else to go to troubleshoot, as this box is soley used for Boxee (I use VLC still for DVDs as I find the controls in Boxee's DVD call not to be intuitive for audio options and the like).