Graphics Card problem

I've just bought and installed a new graphics card (XFX GeForce 5200). I
got it from Dell, so it's a 'good' card (not a dodgy second-hand one !). I
recognise it's not the 'best and newest' graphics card on the marketplace -
but that doesn't mean it doesn't work of course. (someone on here suggested
it was ancient and I should just replace it with a top-of-the-range card.
Hey - you don't need a Ferrari to get from A to B !!)
So.....I want to attach a second monitor to my PC - an new flat panel LCD TV
screen which says it can be used as a PC monitor. The TV monitor is in a
room next to my office - I want to run a cable from my PC to the TV
monitor so I can watch DVDs, and other stuff I've downloaded in that room.
I therefore need to be able to run both monitors AT THE SAME TIME in
'clone' mode. I found out that many graphics cards have two ports (DVI
and VGA) but will only support one or the other at one time, not both at
once. My new
card claims it will support two together. I've connected everything,
downloaded latest driver from website, set up 'clone' mode etc.
Problem - the TV monitor shows all the startup screens exactly as on my PC
monitor when I'm booting up, but as soon as Windows startup is finished I
just get 'no signal'. I've tried changing screen resolutions - no joy.
I've sent emails off to XFX and to LG (the TV manufacturer) but I guess I
won't get a reply till next week because of Easter. I've spent 3 days so
far fiddling with it - driving me nuts.........can any of you clever guys
suggest anything please ?