I'm not sure what stage you are in, or what you are doing as far as construction (new/retro/rebuild?) but, I would consider EVERY possible scenario now for wiring if the drywall isn't up already. Look at how much you spent on wiring - a couple hundred maybe? Now is the time to wire the heck out of everything!
So, for your LCD - you don't want HDMI run behind the wall.
You want HDMI, VGA, component video, s-video, and composite video - at the very least. Just hit
www.monoprice.com and pick up a bunch of cables, should run you 100 bucks max!
For speakers, you have a lot of choices, but eBay offers some great values as does Audiogon/Videogon for areas where you don't need top flight stuff. Keep in mind, you can't just drop a bunch of speakers onto 'zone 2' of a receiver and get killer results - you typically should use a good impedence matching speaker selector and a quality amplifier to handle the audio.
For a receiver and speakers... I would ask around and consider just saving up some money from the start. A good set of mains plus a good receiver is a great start and could easily chew up a couple of grand. Limitless choices out there with Yamaha, Denon, and Pioneer always near the top.
For speakers... Ditto on the choices.
A subwoofer? I think that a good sub is a good sub. The subwoofer is one of the most important speakers you are going to have so going 'cheap' is not the way to go at all... IMO. Just don't get one to start off with unless you can get the one you want. If it's a Velodyne DD series - then start saving... If it's a HSU or Paradigm... start saving! Don't skimp on this speaker or you will be looking to upgrade almost from day one. I went through 3 subs in 12 months and just realize that I should have bought my HGS-18 from day one.
Don't feel like you have to do everything at once. The only thing you have to do is take advantage of open drywall. If you've got things open, then consider running conduit if you think it may help you later.
Finally: You already have a 32" Aquos? I'm asking because it looks like your couch may be on the opposite side of the room at about 14' from the display. At that distance, the Aquos would be a bit on the 'small' side. But, if you have it then you aren't in the position to go bigger yet it sounds like.
Finally - don't forget that you need power at the flat panel location. I recommend simply using an extension cord. That way you can put the flat panel into the same surge supressor everything else is on and it should help to eliminate ground loops.
Good luck!