What's wrong with my Canon Rebel XS?

Hi all,

I bought a Canon Rebel XS about 10 months ago and have noticed that the pictures seem really lackluster, especially (but not limited to) low light conditions. This is my first digital SLR, but I've done a fair amount of (amateur) photography with film-based SLRs so I'm not completely new.

Anyhow, the contrast really became apparent from a few pictures I took this summer when my friend took almost identical pictures with a Canon SD790. That little cheap camera seems to match or outperform the Canon in those shots.

I just don't know enough about digital cameras - are the colors better on the SD790 b/c its somehow enhancing them in-camera? Why can the SD790 often shoot an ISO of 80 when the XS needs an ISO of 200 in the same conditions? My XS seems particularly inept whenever there are both light and dark areas in the frame.

The following sample pictures were taken on automatic mode - which is important because my wife, who also uses the camera, doesn't want to have to mess with the controls. Could something be wrong with my camera, or we making some sort of mistake?

Here are the pictures. EXIF data should be accessible.

Shot 1 - Rebel XS: http://www.flickr.com/photos/alexwood/5193654418/
Shot 1 - SD790: http://www.flickr.com/photos/alexwood/5193053291/
Shot 2 - Rebel XS: http://www.flickr.com/photos/alexwood/5193656710
Shot 2 - SD790: http://www.flickr.com/photos/alexwood/5193658836

Thanks for any advice you can give me!
Alex