Honestly, I would back up all of your downloads, documents, pictures, videos, browser history/passwords/bookmarks, and anything else you want to save to an external drive or to The Cloud (or multiple, e.g., most/all browsers have a sync function, and OneDrive/Google Drive/Dropbox, etc.), and then download and test drive multiple different distros until you find one that you like and has good community support. Nearly all distros today will let you test it out without installing (kind of a try before you buy). Once you find one, install it while wiping the Windows install, then load your graphics drivers and Steam. Steam will handle the rest as far as running your games (some caveats apply, i.e., some multiplayer games will not work because the developers are assholes).