I would consider an upgrade, since support for Windows 98 must be difficult by now. Windows doesn't need to talk to Exchange, but various versions of Outlook have different requirements. I found two links that might provide more pertinent information to your question:
Do you have comments on this Ask the Expert Q&A? Let us know.
Related information from SearchExchange.com:
Dig Deeper on Microsoft Exchange Server 2003
Related Q&A from Peter terSteeg
If recently created mailboxes are not displayed in the GAL after a migration to Exchange 2007, Active Directory (AD) has yet to replicate the ...continue reading
If you are migrating mailboxes across domains after an upgrade to Exchange Server 2007, you will need to update the Exchange Management Console.continue reading
Items deleted before an Exchange Server migration will not carry over to the new server, even if a Deleted Items Retention period is set. Find out ...continue reading
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.