Hi m8,I still havent had a chance to check my set up,but if I remember I could only get 800*600 when I was connecting my pc via that svideo type connection.I couldnt get it to display any higher res than that.
At the moment I have it conencted via dvi(just a standard £10 digital dvi cable)and get get res of 1024*768 no probs.
Have you tried using dvi?What version of windows do you have and what gfx card?