You can certainly move Windows to an external hard drive but Windows will not boot directly from an external drive. If you are running Windows in Parallels (See links below) you can have Parallels installed on the Mac's drive and then have your Windows virtual machine on the external drive.
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.
Of course, backup all your files to an external hard drive and perform a clean install with your Vista disk. They only make it easy to upgrade never downgrade. If you do not have an external hard drive, create a disk partition to use as your file backup.
In general, there is no reason to have more than one partition on an external hard drive. There are some specific cases where it might be desirable but you would know if you had a requirement like that.
Modern disk drive construction more or less requires drives to have at least one partition. Whether the drive is internal or external is immaterial.
The system partition is the active partition of the hard drive and it contains the OS boot record. The boot partition is the partition where the Windows operating system is stored.
There are several tutorials on YouTube which will show you exactly how to remove a partition. Removing a hard drive partition on Windows Vista will create an empty space that you can use to install a new partition. Be aware that it will also delete all data that is on the partition.
The first hard drive or partition.
The C drive in Windows Operating System is the partition on which the OS is installed. It also contains installation files for other programs.
Yes you can have the Mac OS on one drive and Windows on another drive. Or you can partition a single hard drive and have both on the same drive.
The C drive in Windows Operating System is the partition on which the OS is installed. It also contains installation files for other programs.
boot partition
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