Damballah - I'm a person who is also afraid of messing up my computer with one wrong button, but I have to tell you that the directions posted by Lady CFII (which I would link for you if I were not also a twit!) were so easy to follow that I was amazed. I added a bunch of mods two days ago and I feel like a pro (thanks, Lady!). My game is running fine and the purple fire is mesmerizing.
If you follow the equally easy instructions to back up your images file, you should have nothing to worry about. Good luck!