How to keep a local copy of ALL emails in Entourage on Mac.

Here is a our setup:
10 Macs (mostly mac pros, mostly Tiger, some Leopard)
Entourage 2004 (2 people with 2008)
Hosted exchange email with 600MB space
Series of project folders, emails filed from inbox every few days into relevant folders.

Problem:
With 600MB we are regularly hitting our limit and as such we have to archive our email on a regular basis. Thi s involves creating a MBOX file from a project folder, storing that file on our NAS, deleting the emails from the folder, emptying deleted items. This then frees up space for us to send and recieve emails.
The problem is, the largest folders usually relate to the most active projects and as such, when the emails are archived we ALL have to manually import the archive, (into the 'On My Computer' area) if we wish to see emails more than a week or so old.

Aim:
What I would like to do is have a live 'copy' of all our emails and folders on local machines, the process to do this should be entirely automated so that no emails are accidentally missed and not seen. I suspect rules can do this?? This would then allow us to archive emails a lot more regularly without the concern that we cannot see emails from say, 3 weeks ago. All machines have GB's of space so there's no concern about this building up.

I relatively IT savvy and run the systems here but scripting e.t.c is my major weakness, so please err on the side of beginner to start with!

Thanks in advanceStart Free Trial