Turning off password authentication is a great way to lock down your Linux box. This means that no matter how many times someone tries login/password combinations, they'll never get in - even if the username/pass is correct!
You can use ssh-keygen to create keys on your machine - in linux, you use the ssh-keygen command.. not sure how you do it in windows. I do have a couple co-workers that have set up keys in windows and set up putty to use them.
Once you have your key, pop it on the server in the ~/.ssh/authorized_keys file so you can log in w/o giving a password (no matter what your current ip address is or what it'll change to).
Make sure you can log in with your key before you turn off password auth on the server