You can create a custom menu and include only the items you want to include in it. http://en.support.wordpress.com/menus/
Setting up a custom menu is easy as pie, provided you know the differences between Posts and Pages, and the differences between static Pages, (which will never automatically update) and dynamic Categories pages which will automatically update when you publish Posts with Categories assigned to them.
Read this carefully http://wpbtips.wordpress.com/2010/06/30/posts-on-pages/
There are many common errors, misunderstandings and misconceptions when creating custom menus and there are some tweaks you can use to improve your custom menu as well.