Lots of good info but I would add...
...make sure any and all data on the laptop you care about is burned to DVD or a jump drive and you have all the software necessary to get Windows up and running again. OR take the short and sweet route of making an image of the laptop. Hope all goes well and have fun!
I would lean towards the Kubuntu distro. Fedora is also fairly easy on a newbie. Try several but the KDE recommendation for a desktop is a good one.