jon - welcome. If you have surfaced after diving into the pool, help is on the way
If you want HD, you WILL need a receiver to receive it. Options:
1) DirecTV or Dish network. Both have HD selections along with a gang of other channels. Check both of them out. I believe they each have a package that includes an HD receiver.
2) VOOM. I read not so Customer oriented stories about them at the AVS Forum (a place you should really spend some time for research)
3) Cable company.
4) Antenna.
I've listed these options in the order I would prefer . Have tried them all except VOOM and I love my DirecTv. If there is no HD receiver available with any of the options, you will need to buy one. Figure $300-$700 depending on bells & whistles.
Also, you can simply get a receiver, or you can get a receiver / TIVO combo so you can record some shows.
Also, as a newbie, avoid the dreaded "what if" and get what makes you happy. Upgraditis is a very expensive itch to scratch.
Good luck with it and post questions as you need to. All of us started somewhere with this madness and the folks here have a rich tradition of overachieving at spending other people's money.
