Budget Range: $850 U.S.D. After Tax and also After Newegg price checking from Fry's.
System Usage from Most to Least Important: Gaming rig, CS6, Sony Vegas.
Are you buying a monitor: No
Parts to Upgrade: New build.
Do you need to buy OS: No
Preferred Website(s) for Parts: Newegg, Fry's.
Location: Roseville, California. U.S.A.
Parts Preferences: I prefer AMD but realize that Intel is better at most tasks. So, whatever best fits my needs.
SLI or Crossfire: Maybe
Your Monitor Resolution: 1360x768
Additional Comments: I want this build to be able to support Mac OSX Mountain Lion, Lion, or Snow Leopard. I know that sounds like a bit to ask, but I've looked around and asked questions on other sites and they tell me just to go buy a Mac, however I really don't want a Mac, I just want to be able to run the OS. I've read that Gigabyte motherboards are good at it and that Intel CPU's are a must. Realistically speaking this OS is only going to take up about 150GB of space.
I would also suggest a build like the above, however you may want to consider a GTX 660 instead of the HD 7850 seeing that Sony Vegas takes advantage of CUDA cores. However this will cost you about $30 more and it does not worth it to go cheaper in other components (other than maybe the case, but make sure that is still a quality one like this: http://www.newegg.com/Product/Product.aspx?Item=N82E168...
See also here a bit different build at the same money. It actually trades an non-overclockable CPU for a better GPU, the $817 one :