archive my emails with attachments yet be able to refer to it when required.

History: i've been working in a Co for 10 years now and i need to keep referring to emails dated back to the start. I had about 40 gb email data in entourage till last year (in an older mac book pro with leopard) and suddenly it got corrupted. I was told by the service centre that such heavy data on email will get corrupted and recovering from enourage is very difficult. I switched to snow leopard 10.6.8 in 2011 and to apple mail from entourage on my new comp.
Query: I need to know how can i archive my email data and delete from mail box yet be able to refer to the older emails easily when required! Look forward to your solution! Thanks. Preeti

Apple Mail does not work like entourage, you email is not in a propriety database, its in discrete files and Mail just maintains a index to these files. If the index becomes damaged it can just be rebuilt, if one of the emails becomes damaged it doesn't effect all the rest.

So all you need to do is keep a good backup of your Library > Mail and Mail Attachments folders.

You could move all the ones you no longer want into a new Mailbox, export that Mailbox, burn it off, then delete it. When you want to access those email, import them back in again, then delete them. But I doubt that would be a good work around for that many emails.