New HDTV no cable signal?

Hi Community,

My family just purchased a new Sony KDL32-EX400 to go into the parent's bedroom and I'm having trouble getting HD signal or any digital cable channels onto that TV (we already have a main TV in the living room that's hooked up to our only cable box aka the new Sony doesn't have a cable box). When I plugged in the coax cable into the back of the Sony, all I got were fuzzy signals of a few channels under 100 (assumed to be from basic cable). My question is, what do I need to do / purchase in order to get full HD signal into that TV? Would I need to rent / purchase another HD Cable box? If I have to purchase one, where would be a good place to buy one for an inexpensive price?

Thanks in advanced for the information.

UPDATE:

After looking at the coax cable that's carrying the signal into the bedroom, I noticed that the copper wire that's supposed to be expose wasn't exposed much. After exposing the wire a bit more, the signal became clearer. However, we can't receive HD channels per say. We now get weird channels like 7.1 and 5.1 (regular counter parts are 7 and 5 obviously) I also noticed that these new channels state that these channels are "HD" in the sense that on the top left corner is says something like 720p or 1080i (though the latter isn't HD I would say). I haven't looked at the other HD channels that we would normally have that aren't public channels like the History Channel or Discovery Channel, but I'm thinking they wouldn't be there as when I did the auto program it seemed like we only had a total of around 200 channels at most when I know we should have access to around 300+ channels. Anyways, is there a way that we can configure the TV in such a way that the channels correspond to the channels we would normally input in the main living room TV cable box? Once again, thanks for the help, my family really appreciates it.