What is important for choosing an operating system?
Is it important to have a computer that is the same brand and operating system as the computers you use at school?
What is the relationship between a guest operating system and a host operating system in a system like VMware what factors need to be considered in choosing the host operating system?
A host operating system is the operating system that is in direct communication with the hardware. It has direct hardware access to kernel mode and all of the devices on the physical machine. The guest operating system runs on top of a virtualization layer and all of the physical devices are virtualized. A host operating system should be as modular and thin as possible to allow the virtualization of the hardware to be as close to the physical hardware as possible, and so that dependencies that exist in the host operating don't restrict operation in the guest operating system.
Operating system is more important than the application software, in the sense that the operating system is the mother of all software that are to run on the computer. without the operating system, it is impossible for the computer to run. operating system provides a platform for all other software to be installed on. it is actually the main software that supports all other software.
Operating systems has mechanism to protect its own files. When an operating system is running, you cannot modify or edit any important files the operating system need. So like formatting an operating system is nearly impossible. But if you have double operating system (or even PE systems), you can modify or edit files created by the other system. There aren't any rules to constraint you. Hope these are helpful.
A client operating system is generally a single user operating system where only 1 user can be actively using the computer at any one time. Video and audio are important to the 'users' to have a rich experience. A server operating system is a multi-user operating system where it is optimized for multiple user access at the same time sharing all of the resources. Audio services may be limited and the video experience is not very important as many servers do not have dedicated monitors or keyboards (operate headless)