Upgrading from Microsoft BackOffice Server (BOS) 4.5 to BOS 2000 is likely to be time-consuming. The complexity of the upgrade process depends on the number of BackOffice applications you currently use. Adding either new BackOffice applications or applications you haven't used before in your BackOffice mix will be fairly simple because you don't need to upgrade existing configurations.

The first step in the upgrade process is to migrate the server OS from Windows NT 4.0 to Windows 2000. All of the BOS 2000 applications—except for Systems Management Server (SMS) 2.0—have dependencies that require Win2K Server as the base OS.

The most difficult part of migrating from NT 4.0 to Win2K is converting from the domain system to Active Directory (AD). Just as BOS 4.5 required a PDC, BOS 2000 requires an AD structure—whose design you must have ready to go before you begin your upgrade.

The most complex migration challenge is moving Exchange Server 5.5 to Win2K and then upgrading it to Exchange 2000. You must manually perform all the necessary steps (e.g., installing the Exchange 5.5 AD connector) to get Exchange 5.5 updated and working correctly before you can move it to Exchange 2000/BOS 2000.

If you run Proxy Server, the Internet Security and Acceleration (ISA) Server that replaces it is installed by default. You can modify existing settings, but you can also just accept what's offered and go on your merry way. If you want to use the new ISA Server features and/or haven't been using Proxy Server as a firewall or Network Address Translation (NAT), you can run the Internet Connection Wizard both to set up basic Internet connectivity and to configure your firewall.

The SQL Server 2000 upgrade should also be relatively painless, and accepting the defaults shouldn't cause any problems with existing BackOffice applications that use SQL Server.

SMS requires lots of system and network configuration information from you, but nothing that's new to those who have configured SMS before. SMS can be installed only if SQL Server 2000 has already been set up.

SNA Server is now known as the Host Integration Server. If you've been using SNA Server, the upgrade process should be painless.

If you plan to take advantage of the new BOS 2000 feature that lets you install various BackOffice applications on multiple servers, you'll want to check out the BackOffice MultiServer Planning Wizard that Microsoft offers. The most important thing to remember is that you must purchase the required additional Win2K Server licenses in advance.

Keep all this in mind when you begin planning your BOS upgrade.