Woops, sorry, you're quite right. Sorry. My TV can handle RGB so I need to go from a VGA connector to RGB SCART (but I still need a graphics driver which can output 576 interlaced at 25 frames per second)
For SCART you also need to give it composite sync. VGA is normally separate sync. Some video cards can do composite sync directly if set to do so, otherwise you will need an adapter that combines the sync signals. You can build one pretty easily if you are handy with electronics. I know pre-HD Intel graphics could do composite sync, but I don't know if the current ones can.
You should check out the program Powerstrip. It can set custom resolution/timings/etc. Your hardware has to support it, but it will often give you far more control.