If you have a receiver somewhere in your home theatre setup and it is going to your TV then an HD cable would be fine HD out to your receiver then Composite/Coax to your TV (which would already be there) then you would also benefit from the surround sound :)
Also based on the games that you like, I can't believe Demon's Souls wasn't mentioned... Best game this gen so far for me :)
Also Little Big planet is a blast, even if you are younger, or have friends over. I never get tired of b**ch-slapping my friends.
Gaming addict gave you lots of good ones in his list, I have all those as well, all great games depending on what genre you like.
Unicorns ARE real - They are just fat, grey and called Rhinos