2.6 Upgrading to Windows 7
By Val Bakh
Although replacing an older operating system with a newer version is commonly referred to as an upgrade, the exact, technical definition of the term upgrade is more specific. When you are performing a clean installation (that is, when you choose the option to perform a custom installation) on a volume that contains an older operating system, the existing operating system and all installed software and personal data are either completely removed or disabled and a new operating system is installed instead. All applications have to be reinstalled, and personal data can be restored from a backup. If you choose the option to perform an upgrade, the new operating system gracefully replaces the existing operating system while preserving the installed applications and personal data. Not all upgrade paths are supported. For example, an x86 (32-bit) edition of any Windows operating system cannot be upgraded to an x64 (64-bit) edition and vice versa. To perform an upgrade, you always need to initiate it from within the existing installation. For example, to upgrade Windows Vista to Windows 7, you need to boot the computer into Windows Vista, insert a Windows 7 DVD, and click Install now. This means you can never perform a true upgrade if you boot the computer from a Windows 7 DVD into Windows Preinstallation Environment (WinPE).
Generally, before proceeding with an upgrade, you should review the appropriate Microsoft documentation that contains the minimum system requirements and the supported upgrade paths for Windows 7 and review your computer’s hardware specifications. Based on this information, you should be able to determine which editions of Windows 7 your computer can run and whether you should perform an upgrade or a custom installation.
To help you with these tasks, Microsoft provides a tool named Windows Upgrade Advisor (WUA). When you boot a computer into an earlier version of Windows, such as Windows Vista or Windows XP, and then insert a Windows 7 DVD, the Check compatibility online command is presented in the initial Install Windows screen. If you click this command and your computer is connected to the Internet, a Web page will open and provide you with a brief explanation of WUA. From this page, you can download WUA and install it on your computer. Then you can run WUA from the Start menu. WUA will analyze your computer’s hardware and the installed operating system and applications and will generate a report. The report will indicate whether your computer meets the minimum system requirements for Windows 7 and which devices and applications can cause problems. Running WUA does not install Windows 7. If you boot a computer from a Windows 7 DVD, the Check compatibility online command does not appear in the Install Windows screen.
WUA is version-specific. When Windows Vista first came out, it had its own version of WUA, which worked similarly to Windows 7’s WUA. However, shortly thereafter, Microsoft discontinued the Windows Vista version of WUA. Now, if you boot into Windows XP, insert a Windows Vista DVD, and click Check compatibility online, you are directed to a Web page that does not even mention upgrading to Windows Vista and suggests that you install Windows 7 instead.
There are a few other unusual things about Windows Vista. It looks, and quite often feels, so similar to Windows 7 that you may not be able to tell them apart right away. It is not uncommon for a “grandfather” version of a program or operating system not to be directly upgradable to the most recent version. For example, no one is surprised that Windows 2000 cannot be directly upgraded to Windows Vista or that Windows XP cannot be directly upgraded to Windows 7. However, even though Windows Vista directly precedes Windows 7, the original version of Windows Vista (Release to Manufacturing, or RTM) cannot be directly upgraded to Windows 7, and moreover, Microsoft no longer supports it. To be able to upgrade Windows Vista to Windows 7, you first need to install Service Pack 1 (SP1).
Normally, service packs are incremental. In practical terms, that means you can install the most recent service pack without installing any earlier service packs. Not so with Windows Vista. If you are running Windows Vista RTM and want to install SP2, you first need to install SP1. Microsoft states that SP2 would have been too large if it included SP1. However, the main reason is probably that SP2 is not just for Windows Vista but is also for Windows Server 2008. Windows Server 2008 has skipped its true RTM phase and has been released with SP1 already built into it. Therefore, including SP1 within SP2 would have been unnecessary.