The new Microsoft Windows 8 systems that come preinstalled on a new computer have a special feature - a feature no other PC has ever had. By default they are locked down so you cannot dual boot Windows 8 with another operating system such as Linux or even older versions of Windows such as Windows XP and Windows 7.
Dual booting is a popular thing to do for many PC users because it allows them the ability to use the right applications they need to get the job done if those applications are not found on Windows 8 alone. Dual booting is also used in companies that require workers use multiple operating system platforms or home users and students to try out and learn about other operating systems. Many of these operating systems are faster than Windows and have other features Windows does not have, as well as there are things Windows does better than these operating systems like AAA Gaming.
The reason Windows 8 will not dual boot is because Microsoft has insisted that their PC manufacturer partners like HP and Dell ship with a new type of bios called UEFI (Unified Extensible Firmware Interface) and it's feature called Secure Boot enabled. Secure Boot acts as a protection feature that is supposed to ensure your system doesn't have any malware at the time of shipping. It works by checking keys in the operating system against hard coded keys in the UEFI. As these keys are signed by Microsoft, the system will not allow any other operating system to boot assuring you have a clean copy of Windows 8. This has never been done before in the PC market and for good reason - PC Manufacturers don't have problems with systems getting malware before they ship.
PC's that ship with Windows are cheaper because Microsoft buys a portion of the hardware in exchange for HP offering Windows in the computer. The rep told me all the PC manufacturers and Microsoft have this same agreement. I wanted to know why there was no mention of UEFI in the HP documentation or why the tech support could not help me. The HP rep told me many times during our phone conversation that because they are paid by Microsoft, they adhere to Microsoft's wishes and not make it easy on people to learn about disabling Secure Boot so you can dual boot - something that is required by the manufacturers from Microsoft's own documentation called Windows 8 Hardware Certification Requirements for Client and Server Systems.