When it comes to deciding on a projection or TV screen, the first thing to think about is the kind of screen you want or even may need. If the room where you are setting up your home movie theater is large, then you will need to have a home theater projection screen or maybe you just want to go down that route anyway.
I, personally, like the idea of having a drop-down screen, but sometimes you have to have one even in a modest home theater. It converts your living room into a home theater: you recline in your chair; click a button and a screen drops down; click a button and the lights dim; click another one and the movie begins!
However, if you prefer a television screen, then you might be considering buying a new one. They say that a 27 inch screen is big enough, but I do not think it is. I think you need 48-60 inches, but then I'm a baby-boomer and my eyes are definitely not what they were.
If you are purchasing a new TV for your home movie theater, I think you should get the latest model. HDTV is already here and since February 2009 the USA has been committed to High Definition. So, I would make sure that your new television is able to receive it. Then I suggest that the new home movie theater screen is a flat one in order to reduce the annoying glare that could ruin the experience, which could be another reason for opting for a projection screen.
Then you should make sure that your new television has enough input and output plugs for the equipment you plan to use and you're ready. Therefore, to summarize, I would go for:
More than a 27 inch screen
A flat screen
HDTV compliant
Plenty of input and output plugs
Satellite compatibility
I would definitely recommend satellite compatibility for the TV receiver because it is the future or even the near future. If you get a satellite television connection you will be able to store HDTV downloads which you can watch on your new home movie theater set-up whenever you like.