Copy of this office is not Genuine

I have a client who’s copy of Office 2007 Enterprise edition is not genuine. If I uninstall this what will happen to the emails in his mailbox? In addition, when I install Office 2007 pro will the mailbox be restored with the emails, and will I have to set up the pop3 connection?

Background
Its three pc network with no server, on a xp pro platform. I don?t know why they are using enterprise edition that was installed before my time.