Bought Me 2 Ultra Slim 2TB Hard Drives

I picked up a 2-2TB ultra slim Seagate hard drives (USB powered) tonight for $120.74 CAD each (including shipping and taxes). I will use these as a main and a back up hard drive to download all my video, picture and audio files. I might get a third and fourth hard drive later. I need to have multiple copies of everything I do. 4TB can be eaten up awful fast when your saving 1080p raw footage video and long raw footage wave files. Who knows how much storage I will eventually require, if I shoot over many months it could require substantial space, and back up space. If I keep a main and back up drive for everything I do then my work should be very safe. I might be also buying a new laptop devoted to video editing. I want to use Final Cut Pro to edit this project so the laptop will need to be a Apple. Been looking into buying a laptop second hand but the savings do not seem that substantial. It might be better and smarter to go new there.