To redirect before headers are started to be sent (for instance from inside a controller) the following works:
This will redirect to the page called portal.
However if you try to do this from a view then you will get an error message about headers already having been sent.
echo 'Due to SOMEREASON you are being redirected <a herf="' . Mage::getUrl('portal') . '">Please click here if nothing happens</a>';
window.location = "' . Mage::getUrl('portal') . '"
However a tip is to reconsider if you really need to do the redirect from the view, doing it from the controller is a lot easier and quicker.