i have been looking for a new home theatre system and doing some research, but this isn't my area of expertise.  I was like to get some recommendations on systems for a large living room with cathedral style ceiling. 

I was looking at maybe the RF-7 recommened system with the RT-10d sub to replace the recommened one.  I would also like to find a good receiver to power it, if you have some recommendations. 

What is your budget? And how do you plan on listening to it? Music, movies, TV, how loud, by yourself? etc....

The RF-7 package is pretty good, but there's no reason to skimp out on the sub. If funds are an issue, I would recommend a smaller pair of floorstanders and go with the RT-12d instead. You'll want to set the mains to small anyway and let the subwoofer take over.