You're probably doing something wrong. I just tried it and had no trouble at all. Xml is perfectly capable of storing the text and giving it back.
You would need to show us the code you are using to determine what's wrong. Whatever the problem is, Replace isn't the best solution. Even if you think Replace is "good enough" for the particular program you're working on, it is not a good general solution and finding a better one will help you become a better developer.
P.S. What you posted will not produce well-formed XML if the user enters characters that aren't allowed. Try something like: