Change category page layout

Generally category page in magento lies in 3 columns. if you want to change it then you have to do a simple thing. just go to the "catalog.xml" in your "layout" folder and add the following code

<reference name="root">

<action method="setTemplate"><template>page/2columns-left.phtml</template> </action>

</reference>

in the line 81 under
<catalog_category_default translate="label">

<label>Catalog Category (Non-Anchor)</label>