I am on my laptop running windows 7 right now but I built a gaming computer. I purchased a windows 8.1 CD-key and would like to know how to install windows 8.1 on my gaming computer which has an empty hard drive. It does not have an optical drive but I have a 4 GB USB stick. I have heard I can put a Windows 8.1 iso on my usb stick using a Windows tool to make a bootable usb and put it in my computer, go into bios and select it, then install windows 8.1. My problem is, how do I download the iso? I have a Windows 8.1 CD-key that I haven't used. How would I go about putting windows 8.1 on my new computer with just the CD-Key? Thanks