That is decided by first going with a widescreen monitor and choosing from the list of available and supported resolutions for wide screen found in the control panel>display settings. The software and drivers for the video card are what offers or doesn't offer support for those resolutions. Once you have the wide screen style monitor you can even right click on the desktop and go to the "settings" menu found in the display properties.
A right click, a click on settings, a slide of the resoluion size bar, a click on the apply and then ok button, and you are on your way. For adjusting refresh rates if needed you would cancel clicking on the ok button to first go into the advanced settings and open the "monitor" tab and choose from the 60-75htz. drop down list and click apply there to see the screen flicker for a second and then exit there. A few mouse clicks is generally all you need as long as the video card supports the intended resolution.
