No-you shouldn't lose anything. Unless you mess it up some how, that is. All rooting does is give you superuser access (its sort of the equivalent of having Administrator access on a PC). Read through the methods first, make sure you understand how to do each step, and then do it. Also, consider why you are rooting--if you don't need root access for anything, you may not want to take the risk. Anyway, thats my 2 cents!