Although for the popularity and ease of use comes a great responsibility on the users too. Most malware and viruses specifically target Windows based computers simply because they control the vast majority of the market. This means you must be much more careful about keeping your computer safe.
Reason #1 for using Linux (even occasionally, for more important tasks): It's much more safe.
Linux is a separate operating system, completely different than Windows, each a different distro (there are many different versions of Linux, and some Linux distros try to compete with the ease of operating that Windows supplies). HOWEVER, the majority of Linux distros come with the option to boot with a LiveCD. This means that you will not even need to install Linux to begin using it, tasks such as checking your bank account is made easy with Linux and can be done in moments.
Reason #2 for using Linux: You don't need to install the operating system.
Finally, one great example I can think of for using my Linux LiveCD was to pull files off the Windows partition of my hard drive when Windows was beyond repair, and system restore would do nothing. I managed to boot up the Linux LiveCD, navigate to what I needed and put it on a flash drive so I didn't lose anything very important. Another instance is dragging a necessary core windows file back into the system32 directory after it has been corrupted to the point where you cannot boot. This is invaluable.
Reason #3 for using Linux: It can save you in the event of a computer emergency.
There you have it, there's literally no reason why one shouldn't use Linux when they have the opportunity to.
For your convenience, here is a link to a page where you can download a Linux LiveCD to burn to a disc http://www.ubuntu.com/desktop/get-ubuntu/download, this is just a Linux distro that I have personally found very easy to use and work with.
Any comments, stories to tell, anything? Feel free.