1080P on Sony Bravia

I Just purchased a Sony Bravia, 60" LED Television.  The only noticable difference I can tell than on my other smaller HDTV, is the sports channels, and I believe this is because many sports use Sony HD camerasor up-to-date HD cameres to shoot sports. 

Many of the other things in High Def, such as movies, I really cannot tell the difference from my older TV. 

However, a friend of mine has cable, and I can see a huge difference in his picture quality as he has the same 60" Sony Bravia television. 

Does DTV cary 1080p Receivers?  because all the ones that I currently have go to 1080i.  and if they do carry 1080P receivers, will it make any difference on picture quality from 1080i to 1080P receivers? 

I have  top notch HDTV and the quality, except for on sports, is somewhat disappointing to me and I am considering switching to Cable.