Using Magnavox 42MF130A/37 as DVI monitor

[Kale R.]

Hello, I have a Zotac 256MB GeForce 8400 GS graphics card that I just bough and it has both a VGA and a HDMI/DVI port on the back. I have the monitor that came with my computer (VGA only) and a large screen Magnavox [42MF130A/37] TV that has a DVI input option. When I plug my TV in at the same time as my computer monitor, I get only video on my VGA monitor, and no response to the DVI connection. Oddly enough, my TV does not report that there is no signal, rather just sitting at a black screen. I notice my Mac doesn't do much to accommodate a second monitor (i.e. the arrangement option under "Displays" should be visible when both are plugged in, right?).

 

Until now, it seemed my computer was simply rejecting the TV, but when I plugged it in through a VGA connection it appeared under Displays (in System Profiler) as 42MF130A/37.. it also only shows everything in 4:5 aspect ratio, all my widescreen resolutions are disabled, and just go to black screen. Is there anyway I can have both my VGA monitor sitting at my computer desk while I have my big screen TV showing everything I do simultaneously? Or is this simply too much to ask for? Any help is much appreciated, thanks!