Some older cards with TV-out can do component video out via that dongle. Trouble is pic will be squeezed into a standard TV resolution like 720x480i (NTSC). They are OK for watching videos and presentations for work, but not good enough for pixel-perfect gaming, like Groovymame. It will work, but not look good.
If you have a CRT component input TV, you will be much better using the GPU’s DVI-I out (it has the extra RGB pins) via a DVI to VGA adapter. Then get yourself a
GreenAntz RGB to component transcoder from me (I make and sell them) or elsewhere. GreenAntz is a perfect companion to CRTEMU/Groovymame as it simply handles the colour space conversion and mixes your sync in properly, but leaves your video modes alone. Once you have CRTEmU installed it is plug n play. The quality is very close to an RGB TV or arcade monitor.
To order a GreenAntz, contact me by direct message.
http://forum.arcadecontrols.com/index.php/topic,164245.0.html