I bought a new samsung 20 inches lcd monitor. The optimal resolution of this monitor is 1600 X 900. But my system has 810e chipset graphics adapter which gives a resolution of only 1152 X 864 in windows Xp. I have latest drivers version 6.13.1.3198

I have dual boot system, when i use linux i see that the same graphics card supports my monitor and gives a resolution of 1600 X 900. How is this possible? What should i be doing now?