> Whats to stop me from copying over my own 'mysql' data folder over an
> existing one?
> I have already done this today and it allows me to access any
> sitting on the server with root access...
> How can I prevent something like this from happening?
Depends on the OS that you are using.
Windows 9x, you can't stop it.
Windows XP Home, you can't stop it.
Windows nt/2000/XP Pro, you can set user permissions to prevent such
things from happening.
MySQL is only as secure (locally) as the operating system you are
running it on.