Because Windows is so commonly used (if for no other reason), it's vulnerable. For safer browsing, try Linux. It's much more friendly these days, and
Linux Mint is great for non-nerds. You can set up your computer to run Linux AND Windows, choosing which operating system to use when you start up. You can also run Windows software under Linux using something called WINE. What's more, Linux software is Open Source, which means it's free to download.
Linux, like Unix, is built from the ground up with security in mind. It's great! I no longer use Windows at all -- I don't trust it, and I certainly don't like the way it gradually gets slower and slower until you have to do a complete reinstall.