First, make sure to set in your BIOS which card you want as your primary. It should be set under an option called "Init display first". You'd probably want it set to AGP. When windows boots up, it will install the drivers for the cards. After that, in the display settings window, there should be a picture of two monitors. When you click on the monitor labeled "2", click the "Extend my Windows desktop onto this monitor" box to activate dual monitor.