Compensating for the Loss of DOS: The number-one problem that many users will face when upgrading to Windows XP is the loss of DOS. While most users stopped using DOS for games and other forms of direct interaction months or even years ago, DOS has remained in the background. Windows 9.x users are used to having an open environment in which to play games and perform other activities. Microsoft built Windows XP on Windows NT technology, which means that games that used to work may have problems now. You'll also find that security is tighter, making it more difficult to make connections and perform other tasks. Most users will eventually get used to the changes, but working through the issues one step at a time is the best way to go for now.
Plan Your Setup: Windows 9.x was a free-for-all when it came to the desktop. You could try to set up individual desktops, but users could circumvent anything you tried. Windows XP provides better security, which means that planning user setups isn't a waste of time.
Making Migration Easier: One of the tasks I normally perform before I install a new copy of Windows is to save application registry settings. You can find them under HKEY_CURRENT_USER\Software\ and HKEY_LOCAL_MACHINE\Software\. Use File | Export to display the Export Registry File dialog. Select Selected Branch, give your settings a name, and click Save to export the settings. Use some discretion when saving settings. I save applications individually and make sure I understand where all of the settings reside when I do. You'll also want to back up any configuration files as part of the process. Once you install the new copy of Windows and associated applications, you can double-click the REG files to restore the settings.
New Administration Techniques: Administering a Windows XP machine is completely different than working with Windows 9.x. You'll want to familiarize yourself with all of the entries found in the Administrative Tools folder. Administrators can add this folder to their Start menu by checking the Display Administrative Tools option in the Customize Classic Start Menu dialog (right-click the Task Bar, choose Properties, select the Start Menu tab, and click Customize). This feature isn't available with the simple Start menu. Almost all of the administrative tools are Microsoft Management Console (MMC) snap-ins, so you can create custom consoles for your particular needs in addition to those Microsoft supplies by default.
New Security Features: Microsoft is tightening security in Windows XP to make life a little more difficult for crackers. One of those changes is to force outsiders to use the guest account when they don't belong to the current domain. This means that administrators who could access shares in the past may find themselves locked out because they no longer have the required permissions. You can circumvent this security measure by changing the ForceGuest value found in the Registry under the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa key to 0. Setting this value to 1 turns on the forced guest feature.