This is the one I like best: Mail.app - Importing from Outlook and Outlook Express.
Use Eudora Windows to get the job mostly done, then Eudora Mailbox cleaner to finish the task.
1. To properly import all messages, attachments, and address book entries, the files copied from the Windows computer must be arranged in a specific manor.
2. Create a new folder and call it "Eudora Folder". The Desktop is a good place to create the folder.
3. Inside this folder, create three more folders named "Mail Folder", "Attachments Folder", and "Parts Folder".
4. Move the "Microsoft Outlook.fol" or "Outlook Express.fol" folder into the "Mail Folder".
5. Move the contents of the "attach" folder into "Attachments Folder".
6. Move the contents of the "Embedded" folder into "Parts Folder".
7. Move the "Nickname" folder into "Eudora Folder".
8. Make sure Mail.app is not running, then drag the "Eudora Folder" and drop it on the Eudora Mailbox Cleaner icon.
9. Leave all the boxes checked and click OK. (Filters will not be imported because Eudora cannot import the original filters from Outlook or Outlook Express.)