I actually think I've got this working now...

I had to set the "Not For Replication" value OFF on the identity field on all three boxes.

I DID have to alter the...

Thanks for the responses all.

To answer some of the questions...

I'm working with TRANSACTIONAL replication.

Unfortunately, log shipping isn't an option as we aren't talking about an Enterprise edition setup of SQL...

Great, thank you Paul!