assuming you have an identity PK you could do something like this (psuedo-code)

get maxid

@i = minid

while @i < @maxid

begin

begin tran

insert newtable select origtable where id between @i and @i + 500000

check for error

optionally delete from origtable where id between @i and @i + 500000

commit or rollback/abend while

@i = @i + 500000

optionally backup log with truncate_only if don't care about recoverability

end

if you have some non-numeric PK or unique index, simply put TOP 500000 keyfield from origtable into temp table

then do the insert (and optional delete) joining that table to origtable