
Leave the messages on your server. You can choose to leave all your messages on your email provider's server and only delete them from the server when you delete them from Outlook. If you loose your hard drive all you need is the mailbox settings (username, password etc). They'll all come up as new messages but you can select them all and mark them as read.
ETA you can back up your addresses as an archive file or export them as a text file. That can be saved on your back-up drive (because we all have one of those right ;-)) and imported to rebuild your contacts list.