SQL Server and SQL Express Server

On SQL Server I can create a table and for the primary key it allows me to select AutomatedInt (or something to that effect) and I don’t have to worry about creating unique id’s for entries on the table.

However in Microsofts free version, SQL Server Express 2005, the automated int isn’t an option…

There is a uniqueidentifier field but it doesn’t seem to work like automatedint and it is giving me error messages.

Any ideas?