I bought a convertor S-Video component in order to conect it to my Sony trinitron wega.
That signal path is completely flawed.
First off, the S-video output on your card is probably rescaling everything to a fixed resolution (regardless of what resolution you set using the CRT Emudriver). To date, nobody has found a way to output custom resolutions from built-in S-video and component outputs.
Secondly, you're converting S-video (lower quality) and then back up to component (higher quality).
The right way do this is to output RGB from your video card (via the VGA port) and then use an RGB to component convertor (e.g. Kramer FC-14, Shinybow or cheap Chinese unit) to feed your CRT. That way you'll get great quality and your custom modes won't get re-cooked.