With Patch Tuesday taking place yesterday, Microsoft fixed a security bug which affected versions of Windows all the way back to Windows 95. This bug left secure sockets open for hackers to potentially steal data or run malicious code. While every version of Windows does have this bug, it cannot be leveraged unless the user is using software which is listening on a secure port. Regardless if you believe your computer to be at risk, everyone should apply the patch from Microsoft.
Windows has a layer of security called the Microsoft secure channel. This is the code which Windows uses to leverage SSL and TLS which are security protocols. Since the vulnerability resides above the SSL and TLS layers Windows will be open for attack even though SSL and TLS improves. Microsoft has fixed this issue now and hopefully fixed any other flaws which resided in the same stack.
If you just use your computer for accessing content via a web browser or Modern Apps then you should be safe. This bug affects systems which are running software which is listening on ports for connections, like a web server. Highly vulnerable systems are Windows Servers which are continuously making connections and usually always connected to the internet. However, no matter what, all Windows users should apply this fix from Microsoft. Even if you don't use any port listening applications, it is important that your system is secure for potential future use or resell.