workaround to migrate from linux to windows

[cybernet]

Is there any work around? i.e. could i backup my client and restore it on the windows version? i cant really do it all manually, i dont have the username and pass for all my customers, i dont see myself calling them 1 by 1 to get all the user pass they have for their mailboxes, for the website i could do all that myself i guess :/ *sighs* seems so painfull