Oh God, where to begin?

My mom's suddenly gone psychoChristian, and any and all of my things (CDs, files, drawings, games, you name it) are automatically deemed Satanic. I need to know a good method to keep my stuff on my account on my family comp hidden and unrecoverable to all except me. I heard that encryption is a good way, but I don't know a lick about it. I don't care what you say I have to do to keep it totally hidded. I'll kill the freakin' Prime Minister if I have to. I need my stuff hidden, and I need it hidded GOOD. Please help? Please please please please please?