I do video editing with sony vegas pro. My memory in my i7 is no where near 16gb and it doesn't really seem to be used as much as I would think when I look at the usage indicator. My current issue is rendering video after I have edited it. I use Neat Video plugin to clean up my video graininess. It is extremely GPU intensive. I am currently going to try and upgrade from a GTX285 to GTX670 to double my rendering speed. Hopefully, this will improve my needs for the program I use. I would say if possible look at your friends old computer and the usage to indicators to show what resources(memory, drive usuage, and graphics card) are being used up most on his old computer so you can build a computer that fits his needs with his software usage/needs in mind. By looking at your friends old computer this will allow you to allocate money to the best hardware needs not just packing the crap out of the memory and finding it may not be as crucial as possibly a faster harddrive, better processor, or graphics card.