Is there a system primary key associated with each row? Does a system primary key or unique identifier for each row in a table exist? Like @@ROWID, @@IDENTIFER, or some other identifier that uniquely identifies each row regardless of how it was created? Using SQL Server 2000 through SQL Server 2012.
In practical terms from a code or user perspective, no. 

There is one internally (rid) but it is not exposed in any documented system view or function