SQL Express is a good product. It provides a free database server for low-level applications.
However, by default, when installed on a 2008 server, it does not make the logged in administrator account a sysadmin. You do have the option to do this during the install…unless you are installing a program, like LiveNote Admin, that includes a SQL 2005 Express install process. You then end up with a SQL 2005 Express installation that you cannot adequately maintain.
Fortunately, you can add your administrator account to the database with sysadmin access using the SQL Server 2005 Surface Area Configuration tool, which should be under Start/All Programs/Microsoft SQL Server 2005/Configuration Tools. When you open this, you will see a link that will let you add any account (domain or local) to the server as a sysadmin.