Installing Windows 8 to the partition you created:
Verify your BIOS is configured so that the DVD drive is the first boot device (or USB if installing Windows 8 from a bootable USB flash drive).
Disconnect the Internet LAN cable or wireless connection. Disconnect all other non-essential disk drives and external accessories. Note that disconnecting from the Internet will prevent Windows 8 from activating during the installation process. More on activating Windows 8 later.
1) From Windows Vista, insert the Windows 8 DVD / USB and Restart / reboot the computer. Once your computer boots from the Windows 8 DVD / USB, you will install Windows 8 to the partition you created on the drive.
Wait for the splash screen to be replaced by the Windows 8 Language, Time and currency and Keyboard setup screen. Make any changes (if needed) and click the ‘Next’ button.
Click on the “Install now” option located in the center of the screen.
You will see “Setup is starting” message
2) Now enter the product key and click ‘Next’
3) Read and accept the License terms and click ‘Next’.
4) Which type of installation do you want? Choose the “Custom: install Windows only” option.
5) Where do you want to install Windows? Select (highlight) the “Windows 8” partition you created. Click ‘Next’ to continue.
6) Windows 8 will start a series of installation steps. Note: At this point anytime Windows 8 needs to reboot there is no action required on your part, do not touch the keyboard.