Does your forum allow both underscores and spaces? If they type user_1, you could change it into "User 1" before it strikes the db, and then -optionally- change spaces into underscores before listing the username.
No, only underscores. But I still need the lowercase option. I did manage to change the code regarding account creation and log-in, but it didn't work for the UserRights page. Could someone help me with that one? (It just says username doesn't exist.) I can properly fix the rest of the problems as they rise. (or live with them ;) ) I've changed Title:makeTitle, User:isValidUserName, User:getCanonicalName.