I second FM’s recommendation, but recommend Linux Mint. It is based on Ubuntu but an easier transition for windows users. If you have programs that require windows, use the virtualbox virtual machine that comes with Mint. Mint is stable, updated often, and comes with the basic software you need. (Office apps, email, browser, pdf stuff, etc.) As a bonus, Linux runs more efficiently than windows and will breathe new life into older hardware. Download the image and make an install DVD. It gives you the option to test drive Mint running it from the DVD. (Will be a lot slower than if installed but you will be able to kick the tires)
ps. The transition from W7 to W10 is a lot more jarring to the end user than the transition from W7 to Mint. Mint feels like Windows 95 thru Windows 7.
Pick the Cinnamon desktop.