I am not an expert. But my little knowledge with internet and computers tells me that there is absolutely no security offered by any operating system or Antivirus that can protect you from intentional spying. Inside a LAN your computer is easily vulnerable to the pranks of a hacker. Once such a person gets such an access to your computer, he can install spyware that can haunt your laptop or computer till the day the computer becomes unusable. It doesn't even depend on the operating systems you can install on it or how many times you format the computer.