@@ROWCOUNT and delete trigger question

Hi all, I'm trying to figure out a trigger and why it isn't working properly for a database project that I just recently took over. I want to change the trigger to work and have some ideas how, but I want to make sure I fully understand why the previous programmer set up the trigger in this way.

1) Ok, first I need to understand--what is the difference between these three variables: ROWCOUNT, @ROWCOUNT, @@ROWCOUNT? I understand that rowcount is that number of rows being affected in an update or deletion but I'm confused as to what adding the @ sign, or two @@ signs means.

2) Here's abbreviated code for the trigger. I'll leave my questions as comments within the code. Basically I need help understanding how/when/why the @@ROWCOUNT variable changes to hopefully understand why this code is set up this way:

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
GO

ALTER  TRIGGER [dbo].[trgTransfereeTourRealtor_IDRealtor]
ON [dbo].[TransfereeTourRealtor]
FOR UPDATE,INSERT,DELETE
AS
DECLARE @SOMEVARIABLE INT
DECLARE....
DECLARE....


--*****AT THIS POINT, @@ROWCOUNT=1

IF @@ROWCOUNT = 1
BEGIN

--*****AT THIS POINT, @@ROWCOUNT=0,  WHY IS THIS? IT DOESN'T SEEM LIKE ANYTHING HAS HAPPENED YET

      SELECT @ID_TransfereeTourRealtor = ISNULL(ID_TransfereeTourRealtor,-1) FROM INSERTED
      SELECT @ID_Transferee = ID_Transferee FROM INSERTED
      SELECT @ID_Realtor = ID_Realtor FROM INSERTED
      SELECT @ID_RealtorDELETED = ID_Realtor FROM DELETED
      SELECT @ID_TransfereeTourRealtorDELETED = ID_TransfereeTourRealtor FROM DELETED

--******THIS NEXT IF STATEMENT IS HERE I BELIEVE TO DETERMINE WHETHER THE RECORD IS BEING DELETED OR UPDATED
      IF ISNULL(@ID_TransfereeTourRealtorDELETED,0)<>0 AND ISNULL(@ID_TransfereeTourRealtor,0)=0
      BEGIN
               --get key for subsequent delete
            SELECT @ID_TransfereeRealtor = ID_TransfereeRealtor
            FROM dbo.TransfereeRealtor
            WHERE ID_TransfereeTourRealtor = @ID_TransfereeTourRealtorDELETED
               
                --set to zero to avoid the delete trigger on dbo.TransfereeRealtor
            UPDATE dbo.TransfereeRealtor  
            SET ID_TransfereeTourRealtor = 0
            WHERE ID_TransfereeTourRealtor = @ID_TransfereeTourRealtorDELETED
            
                SET @RowCountNum = @@ROWCOUNT

--*****here is where the code "breaks". Since ROWCOUNT=0 at this point, the IF statement is always true
--*****and it posts the error message.
            
                IF @RowCountNum <> 1
            BEGIN
                  SET @ErrorMessage = "SOME ERROR MESSAGE"
                  ROLLBACK TRAN
                  RAISERROR (@ErrorMessage, 16,1)
            END
            ELSE
            BEGIN
                  DELETE FROM dbo.TransfereeRealtor
                  WHERE ID_TransfereeRealtor = @ID_TransfereeRealtor
            END
      END
      ELSE IF UPDATE(ID_Realtor)
      BEGIN
        --****THIS CODE WILL UPDATE THE REALTOR TABLE
      END
END

thanks!
goldy