Migration from Groupwise to Outlook

First of all, don't listen to all the "are you crazy" for switching to Exchange 2000. This version bears only minor resemblance to Exchange 5.5 . I'm a CNE who migrated, with help, 1300 Groupwise 6 users to Exchange 2000. You couldn't pay me to go back to Groupwise now. Exchange 2000 is much easier to manage than Groupwise is. I dispise using the Novell ConsoleOne utility for NDS/Groupwise management. Microsofts Management Console is much easier to use.
As for virus concerns, we've been running Exchange 2000 for 12 months now and haven't had a single virus spread via email. The Novell marketing that Exchange 2000 is a virus headache is a smoke-screen. No matter what mail platform you use, the need to be diligent about virus's is the same. Think back to Nimda, Code Red and Slammer over the last few years. None of these needed email to propogate.

Anyway, in answer to your question. I don't recommend upgrading without help. There are many hours no matter which route you take. We used a vendor that brought in Compusven's mail migration tools in. It does much the same thing as using Microsoft's Groupwise Gateway, but moves mail to Exchange 2000 about four times faster. I don't recommend migrating Groupwise archives if you can help it as it adds significantly to the time per mailbox. Every method will have it's drawbacks, but if a generous pilot phase is called for in the project, you'll have time to work out most of the kinks. One thing to keep in mind about Exchange 2000 is that it's much more dependant upon DNS than Groupwise is. Please make sure DNS is steady and rock solid first. Also, be prepared to learn a lot about Active Directory.