Archives are .PST files, so you can't save an archive outside of one. You can save individual messages as separate files (.MSG files) and they re-open as e-mail messages. Another way to reduce the size of a .PST is to save attachments as individual files and then delete the e-mail that originally delivered them. Again, it's rarely the number of e-mails that causes size problems as much as the size of the attachments.

Do you know how to see the size of each message?