Here's a nice article about that one should not be afraid to use Linux – the distribution used for the examples is Ubuntu.
Read it here
To try them out and see if you want to install, just download a live CD and pop it into your computer. A live CD runs the operating system directly off the disk without making any changes to your computer. If you cant ditch Windows just yet, please note that you can dual boot. You can have Linux and Windows (or even OS X) on the same machine, though you need some extra hard drive space for partitioning. I do this, and it is extremely useful for the odd Windows program I have to use. Plus, you can read the files from your Windows side on Linux too.