Finally got round to hooking up my new card to the TV and I now have this issue. It's definitely set to I/PAL. I can get a colour picture on my main TV if I set the Video Output Format to Composite (even thought I'm using an S-Video cable and I don't have a Composite output on the card) but another TV still only gets B/W. I'm also guessing I'm loosing some picture quality if I set it Composite.
For some reason I can't set the TV resolution to anything but 60Hz. So I'm guessing proper I/PAL is not set.
Using Forceware v66.93.
P.S. I don't have a tab called TV.
Increasing the Saturation slider did not help.