I seen the walmart bf ad and have been pondering the 50 inch Samsung for $798. I can not find anywhere what model this is? Also I know that Samsung also has a PN50A450 model...would it better to get that model instead of say a 400 if that is the case of the walmart one. I don't know much about these tv's. Right now we have a 27 inch Sharp, the console kind, and I would say it is about 9 or 10 years old. I just don't want to spend that kind of money if it is going to be better off to spend a little more and get a better model. Thanks.