Choose the highest resolution you can support
Back on the main SaX2 screen, click the plus sign next to the Desktop option and double-click "Color and Resolution" from the resulting menu. By default, SaX2 only gives you an 800x600 screen, but you can change that by, on the resulting "Currently configured desktop" screen, clicking the Properties button and, on the Resolutions tab, changing the resolutions that are available. Select the highest resolution your graphics adapter and monitor will support, as seen above. Click OK and then Finish when you are done.