If you use Ubuntu you will see it is very similar to Windows in the way you use it. With the default installation or if you use it in 'live' mode, it has icons to click to start most programs running and you will recognize some of the programs because they are available on Windows and Mac OS as well.
I suggest you go to
www.ubuntu.com and download a copy (it is free), burn it to a DVD, instructions are on the Ubuntu web site, then boot your computer from it. That will let you use most of the features without touching any of your existing files so you can experiment as much as you like. When you have finished trying it, you can either install it or just remove the DVD and restart your computer, it will be exactly as it was before the you started.
Brian.