NTSC is the (analog) standard passing into history in Feb. '09 and ATSC is the new digital standard being used afterward for over-the-air (reception by antenna) broadcasts. This changeover affects only the broadcast channels and if you have cable or satellite reception the changeover will happen whenever they find they can't charge their captive audience such a high premium for HD.  
I found no evidence that your set is ATSC ready so if you are receiving your signal by antenna, you need to scurry about and buy a converter for your set. Make sure the one you buy is on the list of 'approved' models to which you can apply the $40 coupon(s).
Coupon & info site