My advice is to go for one with at least xga resolution, the higher the resolution the more expensive it gets too.
Screen wise, I have used powered screens, manual hang ones and plain good old bare walls.
get over to the av forums, its quite an informative forums and you will get plenty of opinions and reviews.
Have got one myself and the quality of picture is excellent.
Have had it for about 5years now. When I bought it large flat screen tv`s were really expensive, whereas now they are really cheap. If I were buying now I would definately go for large LCD tv. As the cost to replace the bulbs, can be anything up to £200.