What to look for in a Screen?

[PaniqL]

Mods - Feel free to movie this , i was not sure where to put it and thought this would be the best place to get the most replies.

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Im not sure what screen to get with my Projector i am looking to get.
This is the room conditions.

1) It will be a light controlled Room with NO Windows.
2) There will Matte black Ceiling and Dark Greyish Walls
3) The Projector will be a Optoma HD82 it has a 20,000:1 Contrast Ratio (If you have any help on projectors or a better one at around the same price please comment)
4) The LCR and Sub will be placed behind the screen so it will need to a acoustically transparent Screen.
5) My Price range is 0-£2000
6) I want a Fixed Frame with a 16:9 Ratio

Many Thanks