By default, right now the tab order is "Your Name or Email", after which is the field about whether you want to create an account or have an existing password, and then is the password field. So basically after typing the username, you have to hit the tab key twice to enter your password as against only once on most sites(if not all). Imo, we are so accustomed to typing the username/password via tabs that it leads to a bit of confusion (or hitting enter without entering the password)
I suggest changing the order to how its default on most sites and actually demarcating the "Sign Up" in a separate block in the same container to the right of the login. It will also be more visible and eye catching that way.