Your budget is extremely tight i recommend saving up at bit more to something like $780USD . Trust me i should know i'm getting a $3000 Setup!
Anyway if you reach $848AUD, $760USD heres what i recommend:
(also this is in AUD so I will convert the price to US at the end)
CPU: AMD FX 6300 $141
Six-cores of updated architecture are just what you need
MOBO: Asrock 980DE3/U3S3 AM3+ $107
One new cpu needs a new Asrock home.
RAM:Kingston DDR3 8GB 1333MHz CL9 $27
For those times when four just isn't enough
PowerColor Radeon R9 280x $349
1080p performance with all settings on high
Cooler Master 500W $59
Unlike high end PCs, this won't need a Thermaltake Tough 1500W to make it go
Lite-on DVD RW $20
To play those old'n day games (e.g. BF2)
W.D. Caviar Black 1TB $92
Speedy HDD
BitFenix Shinobi $64
Nice for the price
Total:$760 US dollars