Computers not doing network boot

I bought a new laptop for my office use. It is Sony vaio and comes with default Windows 8  pro. I try to run corporate image on it but did not run. After a bit of investigation I found the following:

1. shutdown the computer

2. Press 'ASSIST' button on your top of keyboard

3. press 'F2'

4. Go to Bios and change the Boot Mode setting from UEFI to Legacy BIOS

5. Enable Network boot

6. Save with F10

7. Restart the machine and Press 'F12'

Here it goes...

If you like to know about license key:

Windows 8 pro to Windows 7 pro does not need a new lilcense key. But you will have to call microsoft to obtain a single use activation code after Windows 7 is installed.

For details: 

http://www.crn.com/slide-shows/applications-os/240155734/how-to-downgrade-from-windows-8-to-windows-7.htm