As paul said if you have not downloaded new driver and just installed the windows generic driver twin view will not be enabled
download newest driver and install ,once installed reboot,nview will then give you the option you follow wizard
If this does not help, Right click on desktop click properties then advanced
click on geforce tab a box will open on the side There should be a displays option(or something similar) I would select clone as the tv will then be the same as monitor