I am seeing a pattern of confusion regarding S-Video and video resolutions with a lot of users in the community, so this posting is for those of you asking things like "why can't I get HD over S-Video" or similar questions. 

 If you want anything above 800x600, you have to use Component, VGA, or DVI/HDMI outputs.  S-Video and Composite just don't support it.  Even if you can select 1024x768, it's not going to be a good picture over S-Video or Composite.

Building on this, you cannot even get true widescreen resolutions through S-Video or Composite.  Sure, you can letterbox it, or mess with the video timings and get whatever you like, but the bandwidth available over the connector just won't support good video quality at anything above 800x600.  Any "wide aspect" video coming over one of those 2 connectors is going to be virtual/anamorphic or a custom timing that most hardware doesn't support.

In terms of video quality, here's the rundown, from best to worst:

DVI/HDMI (unless you need resolutions above 1920x1200, but that's another thread)
S-Video (up to 800x600 only)
Composite (up to 800x600 only)