Upgrading an operating system is a terrifying thing to do. Very few people back everything up the way they should, and the potential for data destroying accidents is high.
A long, long time ago in 1999 when Microsoft released Windows 2000, they simultaneously released a web-based tool called Readiness Analyzer that tested the system for problems that might occur during an upgrade to the new OS, detecting and reporting incompatible applications and utilities. Readiness Analyzer was useful for a clean install of the OS too, by telling you whether any hardware in the system was unsupported.
Now that Windows XP has gone to manufacturing, Microsoft has released a new version of Readiness Analyzer for Windows XP, called Upgrade Advisor. Anyone thinking of upgrading to Windows XP should first run this program.
As of this writing, the pages above state that Upgrade Advisor is "coming soon," and the plan is for them to be available on September 17th. You should be able to download it from those sites, although the file will be very large, about 50MB. You will also be able to obtain it for free on CD-ROM from local retail outlets.
At the beginning, Upgrade Advisor tells you to connect to the Internet, because it checks with Microsoft's site to see if more recent check files are available. This is a significant feature because as product testing and new products change the landscape, Microsoft can update the system testing performed by Upgrade Advisor. The actual setup program in Windows XP includes the same dynamic component, which is not surprising since it's basically the same code as that found in Upgrade Advisor.
The program then explains that there are two main types of issues it reports: Blocking Issues are ones that will prevent an upgrade (insufficient memory, less than 64MB would be an example). Compatibility Warnings, on the other hand, warn that a hardware or software component may not work with Windows XP, but that the operating system could otherwise function.
Some Compatibility Warnings could be significant enough to make you not want to upgrade. For example, on our test notebook, we got a warning about our D-Link DWL-650 802.11b wireless network card. Specifically, it says that the "Intersil-based Wireless LAN Card Driver" is incompatible with the new version of Windows and will be deactivated on install. (Intersil is the company that makes the chips and drivers in many of the less expensive wireless hardware products. They don't offer Windows XP drivers yet.) We were able to get Windows XP working on the notebook by forcing it to accept the Windows 2000 drivers, but we can't suspend or hibernate the notebook until Intersil writes XP drivers. (And when this happens, Upgrade Advisor will no longer report a problem, because the XP upgrade process will be able to upgrade the hardware.)
We also ran Upgrade Advisor on a Windows 98SE system with a beta copy of Norton SystemWorks 2002 installed on it. SystemWorks 2002 itself is compatible with Windows XP, but as installed on a Windows 98SE system it would be completely incompatible, and sure enough, it reported the individual SystemWorks 2002 components (SpeedDisk, Disk Doctor, and so on) as incompatible. This is no problem for SystemWorks 2002, which can be reinstalled on XP after an upgrade, but if, for example, you're running an older antivirus program and don't have an XP upgrade for it, you may want to hold off on upgrading until you have the new version.
There is also a prominent link in Upgrade Advisor that opens the "Windows Catalog," a Microsoft Web page listing products "...that provide the best Windows XP experience." Upgrade Advisor only works on operating systems can be upgraded to Windows XP. So if you're running Windows 95 or something even earlier, Upgrade Advisor won't run.
Upgrade Advisor in Windows 2000 never got a lot of attention--maybe Microsoft didn't publicize it enough or the press just wasn't interested. They should have been, but with Windows XP, especially Windows XP Home, it's a much more important issue.
In the big picture, upgraded versions have never amounted to a significant percentage of installed operating systems. Upgrades are much more problematic than clean installs and pre-loaded systems. But with the Upgrade advisor, at least users will be able to gauge what Windows XP thinks of their systems before diving in.