AMD Radeon X600 to TV problems

[Inno]

Hi, just bought a SVideo to Scart cable to allow me to watch downloaded TV shows on my TV. Hooked up and there's no picture, no sound, nothing basically.

I've looked about the web and found that I need to select the TV option in the preferences for the graphics card, unfortunately no matter what I try, that option remains greyed out:

I have a screen shot but I'm not allowed to post it at the moment!

Any ideas or is it just not an option?

I'm using a Dell Dimension DM051; Radeon X600 256mb memory card and windows XP - Please ask if you need any more information, I'm not very techie minded!