For some reason windows only supports one playback device at a time. After installing the video drivers, this is the hdmi output now. Rigth click on the volume icon in task bar, goto playback devices and set the standard device back to your speakers. Getting btoh the onboard video and the card to work, can be a bit difficult. By default, the onboard video is disabled, if a second card is found. The 6450 should provide enough ports to connect both monitors to it though.