Hi there,
Just to let you know I have the same kind of problem with my Cintiq 21UX on a Quadro FX 3000 video card, however only at the left and right edges of the screen. Also a slight mis-alignment of the cursor, but I believe this is due to the large screen area in combination with a stationary seat, so my viewing angle changes a lot.
I have used radio controlled keyboard and mice in the past, after changing to cabled versions the jitter was a lot less, so I also think it has to do with interference of some sort...
Reinstalling the Wacom drivers can become a real pain, I feel lucky all is stable now... Oh ja, I have even changed motherboard, processor and memory (from Athlon to Opteron) and still a bit of jitter, but workable....
Hope this helps, good luck!
