Run Duration On SQL Job Doubled After Conversion From 6.5 To 7.0

SQL 6.5 - run duration 6-7 hours
SQL 7.0 - run duration 12-13 hours
175+ columns with total record size=570
4.2M records with tablesize 2.5G

It's a simple 'select into...' with some embedded logic from a work table with all char fields into the actual table converting char fields into various data types (int, datetime, real, etc.) Here is a sample of the code:

SELECT
LoanNum=CASE
WHEN ISNUMERIC(ACCT#)=1 THEN CONVERT(int,ACCT#)
ELSE NULL
END,
PaidToDt=CASE
WHEN PAIDDT = '0001-01-01' THEN NULL
WHEN ISDATE(PAIDDT)=1 AND SUBSTRING(PAIDDT,1,2) = '19' THEN CONVERT(smalldatetime,PAIDDT)
WHEN ISDATE(PAIDDT)=1 AND SUBSTRING(PAIDDT,1,2) = '20' AND SUBSTRING(PAIDDT,3,2) < '79' THEN CONVERT(smalldatetime,PAIDDT)
ELSE NULL
END,
.
.
.
INTO db.owner.tablename
FROM db.owner.wrktablename (NOLOCK)