Thanks.

Can I just check; BOL says about deleting data: "By default, a DELETE statement always acquires an exclusive (X) lock on the table it modifies".

If I break down the deletes into transactional batches - say 100,000 rows per batch, would that cause blocking for the duration of all the batches, or would users queries (inserts/selects) run between each batch, effectively putting blocks on the next deletion batch? So in other words, everything will run, but possibly slower due to waits on everybody else doing their work in the order the statements are performed?

I hope I've explained that clearly! 🙂