After installing Windows 8 on one of my test computers (a Panasonic ToughBook  CF-19), I noticed that I had lost my option to dual boot Windows XP and Windows 8. The new bootscreen for Windows 8 is really nice - it has the metro look, it's touch friendly, and it's mouse friendly - but it didn't automatically add a boot option for my Windows XP installation which was pre-existing on the computer.

Here's how you can dual boot Windows 8 with a Windows XP option.

1. Boot into Windows 8
2. Navigate to the traditional Windows Desktop
3. Open a file explorer window
   I find the easiest way to do this is just to click the folder icon from the start menu
   
4. Navigate to the "Computer" option
   The easiest way to do this is to click the Computer option in the left side of the file explorer
5. Click the "System Properties" button in the ribbon at the top
   
6. Click "Advanced system settings" in the left pane
   
7. In the Startup and Recovery section of the window that pops up, click the "Settings" button (on the Advanced tab of System Properties)
8. Change the "Default operating system" option from "Windows Developer Preview" to "Earlier Version of Windows"
   
9. Click Ok to close the settings popup, then click Ok again to close the system properties menu
10. Reboot and you should be presented with an option to boot into Windows XP (Earlier Version of Windows) or into Windows 8 (Windows Developer Preview).