Just had my new sanyo plv-z4 delivered today

(upgrading from a 2year old z1). the quality is excellent.. however I understand that it needs tweaking to get the best out of it.
can people recommend me settings given the following
its in an almost completely dark room
the projector screen is a fixed one on the wall, a diy job that gives me about 90" by 50" viewing - painted (brushed on

) with total matt white, 4" black border all around (in a satin wood black). - projector is about 140" away from the screen - directly in the middle of the room.
given all the above what should I tweak to get the best from- hdmi - dvd playing at 720p ?
- xbox 360 - via component - also at 720p
there are so many things to change and tweak, I am at a real loss. so

help ???
also my screen is made out the board you get from the back of kitchen units, that white stuff that is 3mm thick, it has about 3 coats of a total matt white paint on it - brushed on. would I see any improvement by going for a sheet of
foamex for example ???