There are several ways in which you could transfer files between a guest and a host. The easiest way is to set up file / folder sharing, and let the guest access the share. Another way is to create an ISO image and load it into VirtualBox; the guest will see it as a CD / DVD drive.
Use Virtual PC (download from Microsoft) and the guest operating system is windows 95. While running windows 95 as a guest, Power chess 98 will run on the guest windows 95 virtual PC OS
It is not recommended that you downgrade. Were you to downgrade, you would just insert the 98 install disk and format over XP or maybe make a partition. But instead, you should download VirtualBox onto XP and install Windows 98 within VirtualBox as a virtual guest computer.
Simple, you install/build a Virtual Machine on your home made operationg system and install Windows as a guest.
If I understand your question correctly, you already have Windows 7 on your PC, and you also want to have Windows XP, Windows 2000, and Windows 98 running as well. The easiest way to do this would be to install a virtual machine and operating system. I recommend VMWare Player, which is a free virtualizing system which is compatible with just about any "guest" OS. For example, I have two flavors of Linux and Windows 98 running as virtual machines on my XP host machine. Other options would include the Sun VirtualBox, or Microsoft Virtual Server. I think VMWare Player is the easiest and most reliable.
Virtual Layer
No - that would involve re-writing the Windows log-in script software. Microsoft does not allow the end-user access to the Windows source code.
A virtual machine is a physical device emulated in software. In current computing references, this means any given software that allows you to run guest operating systems on a given host (e.g. running Windows on a Macintosh computer while being able to use both operating systems at the same time using Parallels or running Windows 95 on Windows 8.1 at the same time using Oracle VirtualBox, QEMU, VMWare, or Microsoft Virtual PC).
These terms are typically only applied in cases where a virtual machine is in use (a computer program that emulates a physical computer), popular examples include VMware, VirtualBox and user-mode Linux. In this case the "host" operating system is running on the physical computer and the "guest" operating system is running in the emulation software. For example I have a workstation running Debian Linux as a host operating system. When I want to compile a program for several versions of windows I can launch several instances of VirtualBox to bring up virtual machines running Windows XP, Vista and Windows 7 in both 32 and 64 bit versions as guest operating systems. This lets me easily compile the program with optimizations for each of these operating systems using a single workstation and without rebooting. Virtual machines are also common in web hosting. There are a number of hosting service providers who's business model consists entirely of selling access to user-mode Linux virtual machines. In this case the Linux guest operating system is actually running in a virtual machine under a Linux host operating system, the benefit of using virtual machines is that each customer may be given complete control over their virtual server, while the hosting company can run hundreds or even thousands of virtual servers from a handful of physical computer systems.
It's usually called a hypervisor, or virtual machine monitor.
Clicking inside the virtual machine window should "grab" the mouse and allow you to operate the window inside. Depending on the virtual machine, it may also have additional drivers ("guest additions") that can be installed in the guest OS to allow seamless mouse movement between it and the host.
Administrator and guest
Linux Visualization software allows a single host computer to create and run one or more virtual environments. For example it allows Linux to run as a guest on top of a PC that is running a Microsoft Windows operating system.