Should links to the PP site and client sites open in a new window?

When the user clicks on the links to the PP site (the "Powered by"-link) and the company web site these open in the same window ( target="_self" ).

Would it not be better if these links opened in a new browser window ( target="_blank" )?

The rationale for this change would be that the user is led out of the PP installation and does not see the log-out button. He nees to enter the back button in the browser to go back to PP. This may be a security issue if he forgets to do that and leaves his computer....