This is a fun place to be...
On the verge of jumping into HD is exciting.
Within your budget, Best Buy carries the 47" Panasonic RP model.
I haven't played with it... but a lot of people love their pannies.
I personally own a 46" Mitsubishi... it can be had for under $2,000 at local retailers. (I paid $2,799 for it less than 2 years ago)
I can recommend the Mitsubishi to you with no guilt whatsoever. It's an excellent television.
As far as the i, and p's of it all go... don't concern yourself too much with it if you don't want to... your TV and STB will handle that for you just fine.
If you do want to concern yourself with it, read the FAQ, then read all you can on this forum.
Good luck to you, and enjoy your HD excursion.
Sets I like:
16:9 of course, if you're going to go HD... do it right.