After you have ensured that your computer meets all hardware requirements for Windows XP Professional and that you have performed all required preliminary tasks, you are ready to perform the actual upgrade. Remember that you cannot upgrade a computer running Windows NT 4.0 or 2000 to Windows XP Home Edition; you must upgrade to Windows XP Professional. In addition, you cannot upgrade a computer running a server version; you must perform a fresh install.

Microsoft also makes an upgrade version of the Windows XP CD-ROM. Use of this version is nearly identical to the procedure displayed here, except that the option for New Installation (Advanced) is not present.

To upgrade a Windows 2000 Professional computer to Windows XP Professional with SP2, follow this procedure. Note that an upgrade from Windows NT 4.0 Workstation proceeds in a similar manner:

1. Insert the slipstreamed Windows XP/SP2 CD-ROM.

2. If the Welcome to Microsoft Windows XP screen does not appear, double-click the CD-ROM drive in Windows Explorer and then double-click the Setup icon.

You can also upgrade by accessing the installation files from a distribution share located on a server on the network. To do so, use My Network Places (or Network Neighborhood in Windows NT 4.0) to map a drive to the distribution share. Then open the Run dialog box and type x:\i386\winnt32.exe, where x is the drive letter you used when mapping to the distribution share.

3. On the Welcome to Microsoft Windows XP screen, click Install Windows XP.

4. The Welcome to Windows Setup dialog box provides a choice of installation type. Select Upgrade (Recommended) to begin the upgrade, and then click Next. You would select New Installation (Advanced) to completely replace your current version of Windows or to create a dual-boot system.

5. The License Agreement screen appears. Read the license agreement, click I Accept This Agreement, and then click Next.

6. The Your Product Key screen appears. Type the 25-character alphanumeric product key and then click Next.

7. The Get Updated Setup Files dialog box appears and enables you to use Dynamic Update to obtain updated Setup files. If you have an Internet connection, you should select Yes, Download the Updated Setup Files. Otherwise, select No, Skip This Step and Continue Installing Windows. Click Next to continue.

8. Installation files are copied and the computer restarts. This takes up to a minute, and involves copying of files to a separate folder on the computer's hard drive. At this point, no change has been made to the old operating system.

9. Press Enter to accept the default of Windows XP Professional Setup from the boot menu.

10. If prompted, insert the Windows XP Professional CD-ROM and press Enter. Then insert the Windows XP Professional Service Pack 2 CD-ROM and press Enter again. This may happen more than once. If informed that Setup cannot copy a file while the Windows XP Professional CD-ROM is in the drive, switch to the Windows XP Professional Service Pack 2 CD-ROM and press Enter.

11. Setup examines the computer's disks, and text-mode file copying proceeds for 5 to 10 minutes, and then the computer reboots again.

12. Windows XP Setup obtains its additional setup parameters from the previous Windows NT/2000 installation. This can take up to 40 minutes. You are asked for additional information only if Setup cannot obtain a required piece of information. You may be prompted for the original CD-ROM as described in step 10.

13. When installation has completed, the computer reboots and displays the Welcome to Microsoft Windows screen. Click Next.

14. The Help Protect Your PC screen enables you to turn on Automatic Updates, which enables the operating system to check for updates on a regular basis. You should select the Help Protect My PC by turning on Automatic Updates Now option. Then click Next.

15. The Let's Activate Windows page appears and prompts you to perform Windows Product Activation (WPA).

16. Similar to the option presented during an original installation, enter your name and the names of any other users in the Who Will Use This Computer? page. You might not see this page when upgrading from Windows 2000 Professional. Click Next and then click Finish.

17. The logon page appears. Click your username to begin.

When you upgrade from Windows NT 4.0 to Windows XP, user files and documents are stored in the C:\WINNT\Profiles\%username% folder for each user, rather than in the Windows XP default of C:\Documents and Settings\%username%. Unlike a new installation of Windows XP, the default desktop contains icons for My Documents, My Computer, and My Network Places.