In fact, I believe I stated wrong what I want: it's a VGA to RGB converter, because the signal will go from the video card to the arcade monitor, right?

Sorry about the mistake, SNAAAAA(...)AAAKE and Dink.
If helps, my video card is a Geforce 2 MX 400 AGP with s-video and composite out. If this doesn't work, I also have a Voodoo 3 2000 PCI card.