That's a nice TV. I have the LN52A850 and love it. The Take series seems to be being clearanced out everywhere. I've seen the Take 5.1 for under $400. I'd just be worried that your room (4100 cubic feel or more) is a bit much for that sized system. If it were me I'd go a bit larger even though it meant spending more money. If funds are tight consider a good quality 3.1 (left & right fronts plus a matching center) system sized for your room and then if you desire surrounds add them later.
Assuming you can wall mount and it won't kill your budget I'd consider 3 of the
Energy Take FPS flat panel wall mount speakers that World Wide Stereo has on clearance for $129ea, perhaps a pair of their
little brothers as surrounds (can be added later when funds allow), and a
HSU VTF-2 MK 3 Subwoofer.
If that's a complete and total budget buster then I'd look at a
Take LCR 3.1 system for $700 and then later, if you decide you want more, add 2 surround speakers and a second matching subwoofer (that's a big room) when money allows. The little Onkyo TX-SR607 has connections for two subs. With a room that size it might be nice to move up to a it's big brother TX-SR707 but it won't make a huge difference.
If you can't wall mount or don't want to then I'd get down to the store and audition large floor standing tower speakers and an acoustically matched center. That's really my preference anyway but wives aren't always friendly to the idea of large towers. Speakers are highly subjective and what any one of us loves you may hate. Go down and give a listen. Listen to Energy, Boston, Klipsch, and Mirage - but for goodness sake avoid Bose!
You can also save money by buying your TV's wall mount and your cables from Monoprice.com. You'll be shocked at the level of quality they sell for 1/3 the price you'd pay at best Buy.