Read about Outlook personal folders in the hits of
There's a personal folder backup tool also, but I've excluded hits about that to keep the picture clear.

Then make such a .pst file and copy the mails you want to keep from your current database into that. Don't forget to compress what's left over.

Accessing directly from cd would give troubles, I suppose, because the file is read-only. And with current hard disk sizes, it doesn't really matter to have an archive .pst somewhere on your hard disk, where it doesn't show up in your regular mail.

Hope this helps.