To add Windows 7 to a system alongside an existing version of Window, you first need to make sure that you have an available partition (or unformatted disk space) separate from the partition that contains the system files for your current Windows installation.
The target partition can be a separate partition on the same physical disk, or it can be on a different hard disk. If your system contains a single disk with a single partition used as drive C, you cannot create a multiboot system unless you add a new disk or use software tools to shrink the existing partition and create a new partition from the free space. (The Windows 7 Disk Management console, Diskmgmt.msc, includes this capability; to shrink partitions on a system running an older Windows version, you’ll need third-party software.) The new partition does not need to be empty; however, it should not contain system files for another Windows installation. Run the setup program, choose the Custom (Advanced) option, and select the disk and partition you want to use for the new installation.
The setup program automatically handles details of adding the newly installed operating system to the Boot Configuration Data (BCD) store.
And how do you edit and configure the Boot Configuration Data store? Surprisingly, the only official tool is a command-line utility called Bcdedit. Bcdedit isn’t an interactive program; instead, you perform tasks by appending switches and parameters to the Bcdedit command line. To display the complete syntax for this tool, open an elevated Command Prompt window (using the Run As Administrator option) and type the command bcdedit /? .
For everyday use, most Bcdedit options are esoteric and unnecessary. In fact, the only option that we remember using more than once in the past four years is the command to change the text for each entry in the boot menu. By default, the setup program adds the generic entry “Windows 7” for each installation. If you set up a dual-boot system using two copies of Windows 7 (one for everyday use, one for testing), you’ll be unable to tell which is which, because the menu text will be the same for each. To make the menu more informative, follow these steps:
1. Start your computer, and choose either entry from the boot menu. After startup completes, make a note of which installation is running.
2. Click Start, type cmd in the Search box, and press Ctrl+Shift+Enter. Click Yes in the User Account Control box to open an elevated Command Prompt window.
3. Type the following command: bcdedit /set description "Menu description goes here" (substituting your own description for the placeholder text, and be sure to include the quotation marks). Press Enter.
4. Restart your computer, and note that the menu description you just entered now appears on the menu. Select the other menu option.
5. Repeat steps 2 and 3, again adding a menu description to replace the generic text and distinguish this installation from the other one.
A few startup options are still available from the Startup And Recovery dialog box (open the System option in Control Panel, click the Advanced System Settings link in the left pane, and click Settings under the Startup And Recovery heading). As shown below, you can choose which installation is the default operating system (this is where descriptive menu choices come in handy) and how long you want to display the list of operating systems. The default is 30 seconds; we typically set this value to no more than 10 seconds (you can choose any number from 1 through 999). To set the boot menu so that the default operating system starts automatically, clear the Time To Display check box or enter 0 (zero) for its value in seconds. These options write data directly to the Boot Configuration Data store.
The syntax of the Bcdedit command is daunting so you may want to use a graphical editor for the BCD store. A utility called VistaBootPRO (vistabootpro.org) includes the ability to repair the Windows boot loader or uninstall it and return to booting from the Legacy OS Boot Loader (Ntldr.exe). VistaBootPRO also works in Windows XP, so you can boot to either operating system and then adjust boot settings. Another alternative, which is equally powerful, is EasyBCD, from NeoSmart Technologies (w7io.com/0211). Both utilities offer the ability to customize multiboot installations and to repair a damaged boot loader or switch on the fly to the old-style Windows XP boot loader.
So how do you remove Windows 7 (or Windows Vista) from a dual-boot installation and restore the Windows XP boot loader? Insert the Windows 7 DVD and type the following command at a command prompt (substituting the letter of your DVD drive for d):
d:\boot\bootsect.exe /nt52 all
You can now delete all system files from the volume containing the Windows installation you no longer plan to use. For even more effective removal, use the Disk Management console in Windows XP to reformat the drive and start fresh.