very new, but very interested

[NoMeGustaU]

i know very little about fp but i was wondering if i should get a 720p or 1080p.
the room has no windows and painted dark brown. the throw distance is around 9-10 feet, and going for 100 in screen. just wondering if it is worth spending the extra money. The fp im looking at is the optoma hd20, is there any other options out there for under $1000? HELP!