$500 AMD build for video editing/rendering & multitasking

Budget Range: $500

System Usage from Most to Least important: tons of video editing/rendering, multitasking, streaming live online, watching movies and the usual online surfing, casual gaming and some photoshop

Parts Not Required: keyboard, mouse, monitors and operating system (already own windows 7 ultimate 64bit)

Preferred Website(s) for Parts: no preference - cheapest and most reliable

Country: U.S.A.

Parts Preferences: AMD set up(looking for best bang for the buck)

Overclocking: not familiar with this, open to either or

SLI or Crossfire: not familiar with this either, open to either or

Monitor Resolution: 1920x1080

Additional Comments: would like to have dual monitor set up, really looking for quick rendering times when it comes to producing videos, and would like to throw any game with decent settings. Thank you guys for all your help and time, as I stated early - trying to look for the best bang for the buck.