Constant stuttering while in windowed mode

[Rez]

Hopefully someone can help me with this issue.

While im playing ffxi in windowed mode i get this constant stuttering however while in full screen mode, everything plays smoothly.

I know its not a graphics problem because it runs at a constant 29 FPS. Plus I have no issues running much higher GPU intensive games like Starcraft 2 borderlands etc

Thanks for the help in advance

EDIT: I should also note that im running in SLI (nvidia) however when i changed all play online games to run on a single gpu, it seemed to reduce the stuttering a little but it was still there.

But like I said before, if im in fullscreen, it works fine, if im in windowed mode, it stutters.