How is this?

Can you see how it could be Improved?

DECLARE @NextIDs TABLE(UniqueID int primary key)

DECLARE @ThreeYearsAgo datetime

SELECT @ThreeYearsAgo = DATEADD(d, -(3 * 365), GetDate())

WHILE EXISTS(SELECT 1 FROM [ISAdminDB].[dbo].[MyTable] WHERE [MyTable].[DateTime] < @ThreeYearsAgo)

BEGIN

BEGIN TRAN

INSERT INTO @NextIDs(UniqueID)

SELECT TOP 1000 UniqueID FROM [ISAdminDB].[dbo].[MyTable] WHERE [MyTable].[DateTime] < @ThreeYearsAgo

INSERT INTO [ISArchive].[dbo].[MyTable] (<Fields>)

SELECT (<Fields>)

FROM [ISAdminDB].[dbo].[MyTable] AS a

INNER JOIN @NextIDs AS b ON a.UniqueID = b.UniqueID

DELETE [ISAdminDB].[dbo].[MyTable]

FROM [ISAdminDB].[dbo].[MyTable]

INNER JOIN @NextIDs AS b ON a.UniqueID = b.UniqueID

DELETE FROM @NextIDs

COMMIT TRAN

END