Most people recommend as a very rough rule spending no more than 1/3 of your budget on the receiver, then about 1/3 on a sub, and the rest on speakers.
You an pick up an inexpensive Onkyo receiver, factory refurbished with factory warranty, from accessories4less.com for around $150. Combine that with the Energy Take Five, and you'll have much better audio quality. Then save up a couple of hundred for a sub.
Your questions are answered:Speaker FAQ HT: Energy RC-50, RC-LCR, Veritas VS Surrounds | Dual CHT SS 18.1s | Denon AVR-888 | modified Dayton SA1000 | Antimode 8033C Desktop: CBM-170 SE | SVS SB-1000 | Audio-GD NFB-11 | HK 3390 Headphone & Portable HE-400 | K612 Pro | HP150 | DX50 | E12