I use Mimedia AND Dropbox, they do the same thing (back up files) but I feel safer with two!! Both free, BTW.
One thing I learned, when you get something popping up that you don't know what it is (might say Security Alert or whatever) Do NOT click on the "X" to close it - that is how the bad stuff gets into your computer. Go to Task Manager (Ctrl + Alt + Del) and shut it down from there. Still hard for me to remember to do that.