Thanks for the heads up Yisehaq,

I see your point on moving objects... I guess a lens upgrade would be the only real solution. Also the canon hoods don't screw into the filter thread, they sort of screw around the out side of the lens front, so reaching the filter to rotate it will be a bit tricky.

I think for the moment, for me a polariser will be most useful on stationary shoots where I have a lot of time to set-up the shot. ie. landscapes.