Help using two arrays in one foreach

[nlkush]

I have two arrays:

1)

$labels = array   ("firstname" => "First Name: ",      //used for labeling a form
				"lastname" => "Last Name: ",
				"username" => "User Name: ",
				"password" => "Password: ",
				"email" => "Email: "
				);

2)

 $_POST = array   ("firstname" => "john ",      //normal output from a form
				"lastname" => "doe ",
				"username" => "johndoe ",
				"password" => "john123 ",
				"email" => "john@email.com "
				);

I then do some validation. If there is trouble, the form outputs again with this :

echo "<form action='$_SERVER[PHP_SELF]' method='POST'>";

	foreach($labels as $field => $label)
    {
    	echo "<label for='$field'>$label</label>
                <input type='text' name='$field' id='$field' value='$value'/>\n";
    }
    echo "<div id='submit'><input type='submit' value='Submit' />\n";
    echo "</form>\n</body>\n</html>";
 echo "There were errors with the data you provided:\n";

The problem with this is every time the form is re-outputted the error message pops up, but all the information disappears. The reason this is happening is because as the form is being redisplayed, the $value variable is not being reset with the $_POST data. Is there anyway i can use a foreach statement to both output the form labels, and set the $value variable with the data stored in $_POST?