I could not figure out which area to place this question.

I have a Toshiba 56hmx96 I just got. Direct has not been out yet to give me my new dish and HD STB.
So for the Super Bowl today I am watching through my old STB. This STB has the option to go out to the TV with RG6 coax or S video. For my viewing pleasure today, which connection will give me the best picture until the new stuff arrives?

I believe the RG6 connection you speak of is the standard coax/antenna-style cable. In that case, S-video is 2 steps above it. Use S-video.

There should be a composite video output as well if there is S-video. If there is, try it rather than the RF output or the S connections. It is a common, but poorly informed assumption that S-video is better than composite in all cases. S-video has the luma and chroma on discrete lines, yes, and avoids the need to filter them, IF they are discrete to start with. This is often not the case in some systems other than VHS. It is not uncommon for cheap sources to take a composite output and crudely filter it at the output to get S-video. Some may never combine it if the video matrix processing has that feature. It depends on the unit. The comb filter in your set may actually look better if your STB has a cheesy filter. The advantage from a wiring view is that composite can be easily run with RG6 itself, while many of the worst made cables on the market for video are S-video cables. RG6 is hard to beat for moving analog video. As was said above, however, moving it as RF is the worst case, because you need to modulate it and demodulate (using a tuner) it, then filter it to get luma and chroma.