A preprocessor or audio video processor is usually for high end home theater systems. I dont know how much money you have available or are willing to spend or what type of quality you are looking for, but this will preserve the high quality resolution(check the max/output resolution of the processor) while converting it. They can be very expensive or a few hundred bucks depending on what you are looking for.
Just do a search on google for "s-video component processor" or "s-video component convert".
You'll come up with something like this
. If you don't want to go that route there are actually many solutions to your problem. Unfortunately all of them involve spending money. (unless there is a way to make your tv output through s-video hooked up by component that your not aware of.)