$1500-2000 for 5.1 Home Theater Setup

Hello Audiogon!

I'm trying to put together a home theater in the basement for my parents. The Room size is about 20' x 12' x 7.5' (LWH).

Here are the components I have...
Magnepan MMG
Adcom GFA545II
Yamaha LPX-500 720P Projector
HDFury HDMI adapter
HTPC - Core 2 Duo, 3GB DDR2, HD4670
Playstation 3 (ordered it today)
I might hook up some older consoles too.

60% will be Music
30% will be Movies
10% will be Gaming

I'm not set on using the Magnepan's and GFA545II, but I do like the sound of them, and if there was a good way to use them for HT then I would.

The components I thought about buying... (I don't mind used/refurbs)
Marantz SR5003 ($450)
eD A2-300 subwoofer ($400)

I'm just not sure what other speakers to get.

you like the maggies, so i'd get an mmg center (around $299 new) and either another pair of mmgs or a pair of the samller on-wall maggies for rears. for a sub, i see a number of used paradigm, hsu, svs and def tech listed for around $300. for a receiver, amazon, accessories4less, et. al. have deep discounts on marantz, onkyo, yamaha, etc., any of which should work for you. i assume you're using your ps3 or computer to play dvds/cds. you can either sell your adcom or use it to power your front speakers if your receiver has preouts.
hope that helps. back to work.