all current 720p and 1080p televisions should have one or more hdmi inputs. if the model you are looking as does not, perhaps you should pick another model.
if you want hd cable then you will most likely need the hd cable box and a hd subscription which is extra. if standard cable (non hd) is okay with you then a standard box is probably okay. talk to your provider.
well... component cables do offer good video as well but hdmi is currently the easiest and best route to take if you have the option. you can get hd over component cables. its up to you and what you prefer.