If you watch football and Nascar in their standard 4:3 format, instead of stretching them, they will look much better. You don't lose any information either, as all you are doing is leaving the image the way it was transmitted instead of distorting it to fit your widescreen.
Making sure they aren't too bright helps too. I'm assuming you have adjusted your set from its original factory-delivered settings, as those are horrible. Pixelization and other compression artifacts are more obvious when the image is overly bright.
The SD channels will be no better through the 942 than the 625. If your old Phillips was a 4:3 50" set, then SD would be better on it than on most new widescreen sets. As the 4:3 sets were optimized for 4:3 SD 480i inputs, while your new set is optimized for 16:9 1080i images and do a great job with DVDs too.