If you are thinking of building dual boot PC with windows 8 and Windows 7, then Windows 8 makes this dual boot very easy and GUI mode compatable.
Windows 8 Boot Manager has important features:
1) user friendly and can be easily handled on tablets and touch display
2) Allows you to choose the default Operating system to boot
3) Boot manager facilate to faster boot procedure for windows 8 and also windows 8 has the fastest boot time for all version of windows
First do the installation of Windows 7 on your PC. check this how to do the Windows7 installation ?
Once the windows 7 installation completed, Partiton the hard drive from Disk managment tool
•Click on the Start menu, navigate to Computer, right click on it and click on Manage.
•Scroll down to click on Disk Management in the Windows Management window
•On the right hand side, it will show all the drives currently listed in your computer.
•In Next, select the drive that you want to shrink, right click on it and choose Shrink Volume.
•Select the volume size and click OK
Once the partition is creted a new simple volume wizard pops up and click OK
Now Reboot your computer and insert Bootable windows 8 USB/ DVD source
Do the Windows 8 installation – check here for windows 8 installation
Note: when installing the windos 8 OS it asks to select the partition where to intsall the windows 8 OS and make sure you select the new partition which was created as described above.
Windows 8 installation completeds and the dual boot will be successfull.
Restart your computer and you will see the options to boot from Windows 7 or Windows 8