Head over to
http/www.projectorcentral.com and start reading reviews on projectors within your price range. Then look for their projection calculator. It can tell you how far from the wall the projector needs to sit.
You'll also need to take a good hard look at the room you want to use. Is it large enough for the projector? Are you able to control ambient light? Can you set up speakers for good surround sound without tripping over wires? Are there any obstructions that need to be taken into consideration (ceiling fans)? How is it going to be connected to your video source and where will those cables run?
As you can see, there are a lot of things to take into consideration, but your next stop should be Projector Central.
-Wolf sends