What to Do If I Want to Install Two Windows in Two Isolated Partitions?

I have a 400 GB hard disk. I want to know if there is any way to divide it into two partitions, A and B, And make their way logically isolated from each other! I have a Windows 7 in partition A and a Windows XP in partition B. And in each window, the OS sees only a 200 GB hard disk

Although the majority of computers come pre-installed with just one operating system, it is feasible to install many operating systems on a single machine. Having two Operating Systems on the same hard drive is called dual boot. This article will tell you how to dual-boot Windows 7 with Windows XP. To keep the two systems from interfering with each other, you need to create a new primary partition for Windows XP. Here are the practical methods regarding two situations:

Situation 1. New Disk

If your 400 GB hard drive is brand new and hasn't been partitioned, instead of using Disk Management to create two primary partitions one by one, you can run EaseUS Partition Master. Its New Disk Guide tool can help you create multiple partitions in one go efficiently and safely.

Follow the comprehensive guide on using EaseUS Partition Master to partition a new disk: 

Situation 2. Disk Already Partitioned

However, if your hard drive is already partitioned, you need to save your data in another storage device before re-partition your disk. EaseUS Partition Master can help you delete all the partitions on Windows 11/10/8/7 PC at one time and then create two new primary partitions. 

Note: You need to clone or back up the data on the target 400 GB hard drive for data security.

Here is a related article that contains a procedure for how to install Windows XP on the New Partition:

Further Reading: How to Install Windows 11/10 on the New Partition