Commit After 1000 Recs

if l want to commit the transactions after every thousand how would l build it into the script?

Begin Transaction

Select a.AccountNo,
a.TransactionNo,
a.TransactionAmount,
a.TransactionDate
Into dbo.test1

From Trans_May_14Aug2002 a,Reds_JuL_Trans_08Jul2002 b

Where ltrim(rtrim(left(a.AccountNo,20)))=ltrim(rtrim(lef t(b.AccountNo,20)))
AND
ltrim(rtrim(left(a.TransactionNo,20)))=ltrim(rtrim (left(b.TransactionNo,20)))
AND
a.TransactionAmount=b.TransactionAmount
AND
a.TransactionDate =b.TransactionDate
AND
ltrim(rtrim(left(a.Product,20))) IN ('PR060','PR061','PR091',
'PR096','PR111','PR121',
'PR122')

AND ltrim(rtrim(left(a.Transactiontype,20))) IN
('TR001','TR003','TR011',
'TR013','TR027','TR028',
'TR042','TR043','TR044',
'TR045','TR998','TR999')

AND ltrim(rtrim(left(a.journaltype,20))) NOT IN
('JT000','JT720','JT721',
'JT722','JT723','JT725',
'JT726','JT729','JT730',
'JT737','JT738','JT739',
'JT740','JT743','JT746',
'JT751')

OR ltrim(rtrim(left(a.JournalType,20))) IS NULL

AND a.TransactionDate > '2002-04-30'AND b.transactionDate < '2002-07-01'

Commit