What do I need to do to convert from WindowsXP to Linux on a personal desktop computer without enough power to run windows7 or newer? Just informed Firefox will stop supporting WindowsXP.
Answer to the question
Knoppix is light, can run from a USB.
Ubuntu is much better, and should also run.
Create a multiboot usb and try several distro's until you find one, take a look at this guide https://appuals.com/how-to-create-a-multiboot-usb-flash/ on appuals to see how to create a multiboot usb.