Thanks everyone for the reply. It looks like the infinity betas might be my best bet. Size really shouldn't be a problem. Mainly I'm just concerned with the best sound quality I can get for that price.
They are bulky and you may want to get stands for them. If you need stands get the Sanus Basic Foundations 24". They are easy to assemble, the perfect height for putting the tweeter at ear level and have enough strength to hold them.
If you have a TV. I suggest a 250 not a 360 for the center. the 360 is a bit more powerful and not quite as good of a match for the 20s. This is my opinion.
Some people say they sound better with the metal grills off.
The Dayton sub is a good match. I suggest an 80hz crossover. Make sure to leave about 2-3 feet in between the wall and the back of the speaker because it's rear ported. Plus you won't get as many boundary effects.
The receiver I recommended is very easy to use and has a good manual. I can send the manual to you if you want it. These things will produced if properly placed and setup. They play brass and highs extremely well because of the tweeter design. They also have good slam for bass when run with the receiver suggested.
There are two colors black and cherry. black is what the beta 20s are auctioned usually. cherry is what the 250 auctions usually. So you may be forced to get a 360. If you want to color match the fronts. At your budget I wouldn't be to picky though. The 250 fit perfectly into my walmart tv stand and matched it in color too.
Stands probably would be a good future upgrade. You can tilt them up to get the sound at ear level if need be until you get the budget for a couple sanus. The sanus come in pairs and go for around 50 each box. For speaker wire I suggest you get this.
http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10239&
cs_id=1023903&p_id=2794&seq=1&format=2
You don't want to run out. And don't forget the rise and fall of the cable.
http://www.roger-russell.com/wire/wire.htm#wiretable
use the above table as a length gauge guide. Some speakers do dip to 4 ohms. So if you want to play it safe use that as your guide.