try this
INSERT INTO Company2.dbo.CUSTVEND
SELECT *
,CASE WHEN DIVISION='DIV1' THEN 'DIV2' END
FROM Company1.dbo.CUSTVEND c1
WHERE not exists (SELECT 1 FROM Company2.dbo.CUSTVEND c2
where c2. ACCTNO = c1. ACCTNO and c1.SUBC= c2.SUBC )
-------Bhuvnesh----------
I work only to learn Sql Server...though my company pays me for getting their stuff done;-)