.....You wont need 64GB ram for mining but for plotting going to be good. ....
that depends on the OS and number of simultaneous threads doing the reads. on win7 for ex, 64GB can handle 10 concurrent threads that handle 20 drives.
I thought on win 7 the the ram usage is ZERO now like in win 8.1?
When you mine, you also need RAM. On my setup, each miner needs 700 to 1000 MB, depending on stagger size (higher stagger seems to need more RAM). On my setup, each miner can do one harddisk, so basically i need to have 1GB * number of disks RAM free when the system is running, before mining is started. Plus some RAM for the wallet. I'm on Windows 7 on one of my pc's and its 24GB ram seems to work okay with 4 * 4TB disks. With Windows 10 the need for extra RAM on top of the 1GB per miner is a lot smaller, windows 7 has a problem with lots of concurrent file reading, it fills up its RAM and page file with file cache data, and starts eating system and process RAM and crashes itself eventually. If you are building something, consider using windows 10. I have two windows 10 boxes mining away, and they run pretty smooth for now, but I have had a few weird issues not related to burst - Windows 10 is stil beta after all. Much less issues with Windows 10, than Windows 7 though - Windows 10 manages its file read cache a lot more effectively.
Windows 10 when released will be free if you have an existing windows licence (as far as i understand it) but the current test versions seems not to concern themselves a lot about older licenses, ive installed windows 10 on a totally wiped SSD and that worked out fine.
There is also a well functioning burst stack for linux, but i have not had the opportunity to test it, so can't really comment on that.