I use a Zinwell bls3000 as my video hub. The inputs are composite video, S-Video, component video, coax (cable TV), and RGB (computer monitor). Then it outputs RGB, S-video, or component video. I input everything including my computer (via an A/B monitor switch), and then output to my projector using the RGB out. It includes upscaling so my standard DirecTV is output at near DVD quality, and DVD quality is enhanced. Since it doesn't handle hi-def it's outdated, so you may be able to pick them up cheap. I doubt that USB can output high quality, even if you found a converter. I'd think you're looking at S-video at best.
