What do you mean by multi-tasking in this context?
e: also a cpu as powerful as that intel is going to be overkill for everything you intend on doing with it except for maybe movie editing, and it's probably a bad idea to spend a shitload of money on something that's only going to give you slight gains in performance in one area of your use.
you'd be better off buying say, an i5 2500k and putting the money you saved to use on an SSD which will give you significantly more noticeable performance gains.
The reason I recommend the i5 is because of the fact that the things you plan to run (games, web browsing, office stuff, I'm assuming light video editing) are not coded to take advantage of the extra cores the 3930k or fx will give you.
Last edited by Eleeleth; Jun 28, 2012 at 03:16 AM.