I assume the converter is YPbPr, correct? If not it's YCbCr. Make sure that matches the component input on your TV. If it doesn't, that's your issue. Did you start the Computer up and then plug the VGA/Component converter into it or did you shut it down, hook up the cables and then power it on? The latter option is what you should do if you haven't. Check your graphic cards specs by going to Run and typing: dxdiag. Under the display tag make sure your card is compatible, this probably shouldn't make much of a difference though since I assume your converter is an external box that has the technology inside of it, but I have seen straight cabling that some PCs can do natively. Depending on your graphics card, you may be able to install additional drivers to it, which may fix the issue as well. I'd try fiddling with the screen resolution and output settings to make them match your televisions in the Control Panel if I was you (although I suspect you've already tried this). Is there an SD option? Try that if it's available, since your video cards maximum resolution likely isn't HD. If none of this works return it get a refund and get a video card that can output Component video as well as VGA (If you're slightly competent with electronics you could install it yourself easily) or if you have an HD television that accepts VGA just use that.
Fortunately, I have an old XP Media Center PC which natively outputs S-Video/Component video which is very convenient for me since its what all of my old PC games run on.
