Well since you are on a forum for Ubuntu Linux this will likely be your first answer. Ubuntu is a great distribution for people who are new to Linux, with very clear instructions on how to set your laptop up with Windows + Ubuntu or only Ubuntu. Simply go to the download page and follow the instructions from there to get started!
Most beginner Linux distributions come with a large feature set such as web browser, office suite, and media players that you won't see included by default with Windows. Each distro also features an intuitive User Interface that should allow you to become comfortable with transitioning from windows fairly quickly. You are likely to find it even more intuitive than the Windows layout!
If Ubuntu is not to your liking you can try several Ubuntu-based distributions that use Ubuntu as a starting point, but will often have different default applications or user interfaces.
Linux Mint - is a popular Ubuntu based distro that combines a different user interface with the default inclusion of many popular plugins and codec's such as Flash and mp3 support.
Pinguy OS - is a version of Ubuntu that includes tons of default applications to fit every users needs, and focuses on providing a enjoyable out-of-the-box experience for all users.
Elementary OS - is a distribution based off of Ubuntu that emphasises a clean user interface with elimination of clutter and good-looking, simple applications. This distro is new in the game, but certainly one to watch.
And remember that you are more than welcome to try all or any of these distributions without affecting your laptop! Simply download the .iso, burn it to a CD, and restart your computer with it in the drive. When prompted, select "Try operating system" to give the distribution a test run before installing! If you decide you like it, you can run the installer from within the test run.