Intel Quad core or Six core?

I do realize that a 2011 LGA Six Core can be a bit of overkill for the price, but I'm doing a DYI computer that I hope to keep future proof for at least three to six years through HS and College, so I'm wondering if I should get a Quad-Core and a GTX 780, or a Six-Core and a GTX 650.

I'm not much of a hardcore gamer but I tend to do virtual machines, movie downloading, disc encoding, video editing, CPU-intensive games like Minecraft, and maybe the occasional high-quality game (WoW, Skyrim).

Which pair-up is better?

Video editing is very CPU demanding so faster and more cores will be better, more RAM too.

Not much will utilize all six cores. Once you go over four cores then clock speed matters more.

Encoding & video work uses the CPU so more cores the better. Virtual machines (IIRC) are RAM dependent, so IMHO, get the 6-core processor, as much RAM as you can afford, & the GTX 650.

The video graphics cars with its dedicated memory might be as important. Always go with the better, more powerful hardware.
What you might get by with tomorrow, might be insufficient a month from now.