First of all you have to have your monitor and display card properly configured. If they are, go to display properties and click on the advanced button. Under the Adapter tab, there should be a button at the botton called "list all modes." Open this and you can choose any of the supported modes. Double click on one and click on the apply button. This works with my Matrox G400 and LG Studioworks 995E, using the built in XP drivers.