The main thing to remember is that in SQL 2000, users used to own the objects. A user and a schema were one and the same thing.
In SQL 2005, the schema owns the objects, and the user owns the schema.
Therefore, when upgrading from SQL 2000 to 2005, the user who owned the objects is automatically converted into a schema. You ahve to go an extra mile and create a new user in 2005 and link the user to the schema.
For more details please read on the links below…
And tracking deprecated stuff in SQL 2005: