Sounds like her contacts might not be on the computer to sync. You would need something like Outlook or Windows Contacts holding the contacts for iTunes to read it.
And what so you mean by 'Windows Mail'. Is she using an email from Windows (hotmail.com, live.com, msn.com)
If so then her contacts are likely on the server. If so then she might only need to set up that email on her iPad and sync them directly
http://support.apple.com/kb/ht1694