Walt, so far as better sound goes, you certainly should go with the new sub and speakers. A new player or amp would probably do little or nothing for sound quality and should be left for last. Incidentally, relating to your comment about not having room for back surrounds, have you tried the Virtual Matrix feature on your 1075 to create virtual back surround on 5 channel material?
If despite your comment that your list wasn't in any particular order, your itch for the projector and screen is number one, in the absence of Sushi I'll suggest that it wouldn't be a bad thing to do that first if it fascinates you.
