Hi, wrreynolds ...
If you are still using Windows on the computer for which you bought the ISO, according the the copyright, you'll need to install it on that computer. If you still want to use your old windows installation, you'll need to install linux dual-boot. If you've sold the computer, so that someone else is using it, you can't legally use the ISO on another computer unless you get a new installation key for it.
In my situation, I recycled the old computer, removing the hard drive beforehand, and destroyed the hard drive. That allowed me to use the installation key on another computer, and I've used it to install windows 7 under vmware, which is installed in linux/ubuntu. I boot only into linux, and use windows only under vmware, once a year, in order to run turbotax.
