Video editing PC help

So my friend needs a computer for video editing. Mainly using AVID Media Composer as the software to do so. I'm completely inexperienced building a workstation PC and I was wondering if the parts I picked out would work well on a $700ish budget. The graphics card was the most difficult choice because I know nothing about picking out a "professional card" or whatever for a workstation.

Components:

Motherboard/Processor/RAM/etc..
http://www.tigerdirect.com/applications/SearchTools/ite...

Graphics Card
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Heatsink
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Harddrive
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Any help would be greatly appreciated.