you can select the video display on pc and TV, TV alone or PC alone. I beleive it's ALT-P. You can also get to it through the control panel. This is typically use for connecting a projector to the pc.
I have an Acer M5640 Tower PC connected to a Samsung LA32A450C1D LCD TV via an HDMI cable running Vista Home Premium. The desktop is displayed on the PC monitor via an VGA cable. I have gone to DISPLAY SETTINGS and ticked the 'extend the desktop to this monitor (2) box' and the monitor (2) is highlighted. I press OK and then a small menu appears to ask if I wish to keep these settings? Which monitor it refers to I do not know so I've tried both, to no avail. i.e. I still do not see the desktop on the TV screen.
What am I missing?