How to install dual-boot Windows 8 on a Windows 7 PC
If you're planning to get Windows 8, but also planning to keep Windows 7 around for compatibility reasons, Rick Broida of PCWorld has steps lined up for setting up a dual-boot configuration on an existing Windows 7 PC.
The first step entails creating a partition of at least 20GB for Windows 8 64-bit, though Broida recommends at least 30-40GB of space. Next, get Windows 8 and put it onto a USB flash drive for installation. Though Broida refers to the Release Preview versions, developers and IT professionals would already have access to the Release to Manufacture, or RTM, version via MSDN and TechNet respectively. In these cases, simply use the product license key provided by Microsoft (NASDAQ: MSFT).
As not every machine is configured to boot into a flash drive by default, make the necessary adjustments in the BIOS if your existing Windows 7 boots up. When the Windows 8 installer starts up, choose "Custom" instead of "Upgrade." Finally, click on "Drive options (advanced)" and select the new partition that was created earlier.
Once Windows 8 finishs installing, plug out the USB flash drive and reboot. You should be able to see a start-up menu with the option to boot up either Windows 7 or Windows 8. If there is no manual though, log back into Windows 7 and run the "Dual-boot Repair" that comes with free Visual BCD and click on "Automatic Repair." This last bit of advice comes courtesy of user BoYans on the TechNet forum here, and pertains to the RTM version of Windows 8.
- check out this article at PCWorld