hi need a little help please

hi im trying to turn my spare bedroom in to a litte cinema room but its not very big . its about ( L ) 12 ft ( W ) 8 ft and ( H ) 8 ft . i got the lg 42 550t tv for it and not sure if i can use a 5.1 home cinema systerm for the size of the room or what ones i should be looking at floor standing or the small ones . the tv and that is goin to be wall mounted . any help would be great as been doing reseach for a few hours and could not find much help with it . many thanks

im in the uk so no zip code but im look at about 300 - 400 pounds and got ps3 and sky hd box but was goin to use arc to do the sound i think