Two options: Partition your current hard drive. Buy an external hard drive. Changing your operating system should not take more than thirty minutes.. I do it all the time. I'm typing on an OS that is barely a day old.. If you keep all your stuff on a partitioned or external drive then changing your OS is easy peasy. You can't trust antivirus programs.. you can't trust malware scanners.. you can't trust firewall programs.. What can you trust? You can trust that they have to scan and then install or break your current system.. this takes time.. What if you keep them scanning because you keep changing their first step? Again, I doubt you have anyone on your trail.. Simply stated: You are not that important. But just incase; follow where I am leading you. If you use windows.. dual boot with linux Partition and then encrypt a secondary drive that holds everything you want to keep. Use a router to connect to the internet.. a good one. Questions on how to do this? Ask