Well, it's here. And you're sitting at home with Windows 98 or at work with Windows NT and wondering what you can do about upgrading to Windows 2000. A quick look at the Microsoft Web site betrays a bewildering number of Windows products, including the recently released Windows 2000 Professional, Server, and Advanced Server editions. And DataCenter Server is a few months down the road. Adding to the confusion is the number of existing Windows products out there: Windows 3.x, 95, 95 OSRx, 98, 98 SE, NT 3.x, Windows NT 4.0 Workstation, Windows NT 4.0 Server, Windows NT 4.0 Enterprise, Windows NT 4.0 Terminal Server, NT 4.0 Embedded, and even Windows CE.  And did I mention the various beta versions of Windows 2000, such as Beta 3, RC1, RC2, and RC3? And let's not forget MSDN.

It's a mess.

For many of these products, there's an upgrade. But which products will upgrade to which versions of Windows 2000? Let's take a look. 

Upgrading to Windows 2000
The Windows 2000 upgrade picture is pretty much common sense until you really look at the big picture. If you're running Windows 9x, for example, you can upgrade to Windows 2000 Professional, but not any members of the Server family (Windows 2000 Server, Advanced Server, and Datacenter Server). That makes sense, of course. But the same is true of NT 3.51/4.0 Workstation and even Windows 2000 Professional: None of them will upgrade to Server. Let's take a look at the upgrade grid:

 

Windows 2000 Edition that you're trying to upgrade to...

Upgrading from...

Prof. retail

Prof. upgrade

Server retail

Server upgrade

Adv Server retail

Adv Server upgrade

Datacenter Server

Windows CE (any version) No No No No No No No

Windows 3.x

No

No

No

No

No

No

No

Windows 95/98/98 SE

Yes

Yes

No

No

No

No

No

Windows NT 3.51 Workstation

Yes

Yes

No

No

No

No

No

Windows NT 4.0 Workstation Yes Yes No No No No No

Windows 2000 Professional (Beta 3+)

Yes

Yes

No

No

No

No

No

Windows NT 3.51 Server*

No

No

Yes

Yes

Yes

No

No

Windows NT 4.0 Server

No

No

Yes

Yes

Yes

No

No

Windows NT 4.0 Terminal Server

No

No

Yes

Yes

Yes

No

No

Windows NT 4.0 Enterprise Edition

No

No

No

No

Yes

Yes

Yes

BackOffice Server Small Business Edition 4.x

No

No

No

No

No

No

No

NT 4.0 Embedded No No No No No No No

Windows 2000 Server (Beta 3+)

No

No

Yes

Yes

No

No

No

Windows 2000 Advanced Server (Beta 3+)

No

No

No

No

Yes

Yes

Yes

Windows 2000 Datacenter Server (beta)

No

No

No

No

No

No

Yes

* Windows NT 3.51 with Citrix is not a supported upgrade path to any version of Windows 2000.

Confused? Don't be alarmed, it is confusing.  The short version goes like this: Windows CE, Windows 3.x, and NT Embedded can't upgrade to anything 2000-related. Windows 9x, NT 3.51/4.0 Workstation, and any beta of Windows 2000 Professional from Beta 3 on (including RC1, 2, and 3) can upgrade to Windows 2000 Professional. After that it gets a little more obtuse: For example, NT 4.0 Server can upgrade to Windows 2000 Server and the full version of Windows 2000 Advanced Server, but not the "upgrade" version of Windows 2000 Advanced Server. Yeah, that's weird.

Versions of Windows 2000 on CD
In addition to the various Editions of Windows 2000--Professional, Server, Advanced Server, and Datacenter Server--there are also various versions of these editions. Microsoft calls them "flavors," a word that I find despicable. You might also think of them as SKUs. In any event, there are five basic versions: 

  • Retail (full and upgrade): The version you see in boxes in retail stores such as Best Buy. Microsoft refers to the "full" and "upgrade" products internally as variants called Full Packaged Product (FPP) and Compliance Checking Product (CCP) respectively. So the Windows 2000 Professional Upgrade you buy in the store is really a compliance checking product variant of the retail flavor of Windows 2000 Professional Edition. Cute, eh?
  • OEM (also in full and upgrade variants), or "Original Equipment Manufacturer." I call these people "PC makers," though you sometimes see Windows bundled with other hardware, such as hard drives. Functionally identical to the retail version without the box. OEM versions sometimes come with vendor-specific user manuals as well.
  • Select: Available through the Microsoft Select program, where enterprises work directly with Microsoft to purchase software solutions. This program is specifically designed to give large companies big discounts on large purchases. For the most part, software is shipped in a single box with a pad of client access licenses (CALs).
  • NFR (Not For Resale): Microsoft provides these in a variety of ways to certain customers, including the press and its own employees through the Microsoft Store in Redmond. NFR copies of Windows are exactly what they say they are: Not for resale. One small limitation on the NFR version of Windows 2000 Server: It's limited to 10 client connections to prevent companies from installing this in production environments.
  • Evaluation: 120-day limited versions of Windows 2000 that are not limited in any other way. That is, aside from the usage limitation, evaluation versions of Windows 2000 are otherwise functionally identical to the retail and OEM versions.

However, I'd add a sixth version to this list. Remember MSDN? MSDN Universal and Professional members get Windows 2000 on CD as well. So let's also add this one:

  • MSDN (Microsoft Developer Network) : The versions of Windows 2000 Professional, Server, Advanced Server, and Datacenter Server that are shipped as part of MSDN Professional and Universal are functionally equivalent to the full Retail versions, not the upgrades. So MSDN members get the full deal, not a version that is limited in any way other than by license.

So what are the upgrade paths between versions (or, ugh, "flavors") of Windows 2000? They're disgusting, to be honest: Check with the Microsoft Windows 2000 Upgrade site to be sure. But the short version goes like this: BackOffice SBS, Windows 3.x, Windows CE, and NT 4.0 Embedded can't upgrade to any version of Windows 2000. Windows 9x can upgrade to any version of Windows 2000 Professional, but not to any Server Family product. Windows NT 3.x/4.x can upgrade to any version of Pro, but no versions of Server. It goes on, but you get the idea.

Now for some version trivia: Product keys for one edition (say Professional) will not work on another edition (Server, for example). You cannot upgrade an evaluation copy of Windows 2000 to an upgrade version, you must use the full version to upgrade an evaluation version. Another case where the full version, not the upgrade version, must be used to... upgrade. Curious.

Conclusions
The Windows 2000 upgrade is going to cause headaches in a lot of corporations, so it's something worth looking at closely. As always, Microsoft is the end-all when it comes to this kind of information, because they'll have accurate explanations for the exact versions, editions, and whatever else you'll need, not to mention the inevitable CAL issues, which is another topic altogether. But like anything else in life, it all comes down to common sense: You can't upgrade Windows CE to Windows 2000 Professional, for example, but then why would you expect to be able to?