Assuming that the emails are still on the servers, she should only have to set up the accounts in Outlook. They should download properly. As for the emails that she stored locally, I would say if you can, export them to a file that Outlook 2007 can import (or to a pst file, if you can). Then import them (or open the pst file) into Outlook.
Have a great day

Patrick.
**Please note, that I'm new to Zimbra as well, so I'm not sure about it's export/import capabilities. Someone else may have a better suggestion for you.