You might try going into the Picture Menu and turning the AutoMotion Plus option to "Smooth" or "Off". That should fix the high motion issues.
However, for the "jagged" or "blurred" edges, this is likely an issue inherent with SD programming. HD programming will be a huge difference. Enough of a difference that soon after getting HD, you'll be able to distinguish HD from SD just by looking at the picture.
Just purchased the 1080 120h flat screen (LN46C670), hook it up to a Dish duel receiver, (standard definiton). Intial settings of tv were ok, but have notice during high speed motion the imagine seems to blurr at the edges where the high speed occured and takes a second to "refresh" I'm guessing. Overall some channels look pretty good but others look "jagged" Is this just because I do not have a HD receiver? or could it have something to do with my coax or connection? I have checked everything and seems ok. I have not tried a blue-ray or DVD as of yet and I do plan on upgrading to a duel HD receiver.