Well, I understand the technical details of Composite/Baseband, Y-C/Svideo, and YPbPr/Componant, and their advantages, but I think the improvement is marginal at best for 480i output..
The color seperation of Svideo is purely to Luminance (basically, a black-and-white picture), and Chrominance (all of the color data combined), where Componant is YPbPr, or Luminance (all of the green data, since the video sync is on green), the Blue Chrominance data (Pb), and the Red Chrominance data (Pr)... essentially RGB video, with sync on green.
Its not a problem of resolution, but definition.. each method is less lossy than the prior.
I guess my real point is that if you are going to put the effort to put the port on there, you could put the effort into either programming the cpu to do, or upgrading the cpu to handle HD data.