Error Reporting From SP To .NET Code, How??

Hey

ASP.NET 2.0 + MS Sql Server 2005 Express (that version which comes with VS2005)

This code below fails. The Delete method executes a stored procedure, but somehow this SP fails. The SP shown here is a short version of the actual SP. As you see from the code below, there are no way the Delete method can know if SP executed successfully. I assume I just could have returned @@error, but that just gives an error number, and not the description of the error??.. And how should I capture exceptions like these??  How should code this SP so it report the error??

Any suggestions??

public override void Delete(System.Guid id, int user)
{
    using (SqlConnection cn = new SqlConnection(this.ConnectionString))
    {
       SqlCommand cmd = new SqlCommand("SendMessage", cn);
       cmd.CommandType = CommandType.StoredProcedure;
       cmd.Parameters.Add("@id", SqlDbType.UniqueIdentifier).Value = id;
       cmd.Parameters.Add("@user", SqlDbType.Int).Value = user;
    }
}

ALTER PROCEDURE dbo.DeleteMessage @id uniqueidentifier, @user int
AS
BEGIN
 UPDATE table_A set column_A = 1 WHERE Id = @id;
 DELETE FROM table_B WHERE Id = @id;
 IF (@@error = 0)
  COMMIT TRAN;
 ELSE
  ROLLBACK TRAN;
END