Layout-switching in drupal zen subtheme

I just did somethign wrong when creating my own drupal theme by makin a subtheme of the zen theme from the STARTERKIT:

I copied the file layout-fixed as it is without changing it's name to layout.css - which seems to be what you have to do, and what the nice helper script does.

But I want to be able to change between the fixed and the liquid setting in the admin menu.
How can I do that?

I add this to theme-settings.php:

$form['themedev']['zen_layout'] = array(
'#type' => 'radios',
'#title' => t('Layout method'),
'#options' => array(
'border-politics-liquid' => t('Liquid layout') . ' (layout-liquid.css)',
'border-politics-fixed' => t('Fixed layout') . ' (layout-fixed.css)',
'#default_value' => $settings['zen_layout'],

that to
settings[zen_layout] = border-politics-liquid
And remove the stting that loads "layout.css"

and this to template.php:

* Add stylesheets only needed when Zen is the active theme. Don't do something
* this dumb in your sub-theme; see how wireframes.css is handled instead.
if ($GLOBALS['theme'] == 'henning_zen') { // If we're in the main theme
if (theme_get_setting('zen_layout') == 'border-politics-fixed') {
drupal_add_css(path_to_theme() . '/layout-fixed.css', 'theme', 'all');
else {
drupal_add_css(path_to_theme() . '/layout-liquid.css', 'theme', 'all');

(not forget to change "henning_zen" to your theme name!

Another option to use another layout without file renaming would be to change the value of the layout setting.