Windows 7 is a software operating system and is able to use many different kinds of drives - hard, mini, and soft
During installation, Windows 7 will need about 16GB on a hard drive.
The hard drive stores the Operating System. Like for example : Windows XP or Windows Vista or even Windows 7 without the hard drive your computer will not turn on.
When you are getting ready to install the OS, either Windows 7 or Windows XP. It has an option to Format or Partition a hard drive. If you use the partition function you can decide how much you want to take out of the hard drive storage.
Windows 7 and Windows XP are operating systems. You cannot format operating systems. But you can format your hard disk or hard drive. You can use Windows XP bootable CD to format HDD, but you will have to use Windows 7 Bootable Installation disk to install OS on your formatted drive.
It depends on type of Windows 8 installer. If it is update, you need Windows OS preinstalled. If it is full installer, you can install it on a bard hard drive.
You can install Windows 7 from optical drive (CD, DVD), hard drive (a local copy), network or USB device.
NTLDR will default to \Windows on the first partition of the first hard drive.
I just did a clean install of Windows 7's Release Candidate, and my hard drive had 11.7GB used.
I use a Windows 7 HDD drive in my home computer. It is fast, and reliable.
Yes, you can delete windows 7 by formatting your drive, but all of your files will be gone. If you have two hard drives, you can either copy your data from one drive to the other or put xp/vista on the second one and use the windows 7 drive as a slave.
I would suggest installing windows on one hard drive, then installing ubuntu on the same hard drive. Use the other hard drive for the backups (partition it).
You would need to buy Windows XP and install it on your hard drive to replace Windows 7. However there are programs that can run a simulator of XP while running Windows 7.