Roaming Profiles and Outlook (Express)

The site I’m currently getting up and running has a mixed Windows Environment and they want to be able to not only get their documents no matter which machine they logon to, but also their e-mail.

I’m going to be setting up roaming users profiles to help them keep their home directories and documents no matter where they sign on, but I’m not quite sure how to implement the email portion of this.

A majority of the machines are running Windows XP Pro and the server is Windows 2000. However there are a few 98SE machines kicking around.

Some clients are using Outlook 2002 and some are using Outlook Express 6. Should I upgrade them all to Outlook 2002 or 2003? Should I get them all up to Windows XP Pro?

Let me know what your input is on this, and if you’ve run into the same issues. Any help is greatly appreciated!