Auto-user creation issue with OS10.6 clients

We're having an issue where if a user is created via Workgroup Manager (LDAP) and matches the local user's account credentials on their Mac (or possibly not) it will automatically add iCal calendars and things of that nature – i'm pretty sure i've seen this dialogue when creating a new account, it prompts whether you want Mac OS X to auto configure things for you. My client hasn't mentioned they've seen this dialogue but it rings in my mind. Does anyone have any idea how to disable this feature via the Server? It seems only related to 10.6 clients and servers. It is causing clashing of calendar issues, that don't particularly work either. Many thanks.