There are computer programs that simulate computers. These are called virtual machines. You can have a virtual machine that runs your old operating system (providing you have an installation copy) and software (ditto) as well if not better/faster than the original. They are often used for software testing especially for programs that need to run on different platforms. You don't have to buy several different computers for testing, only the emulation software. The assumption made is that virtual machines can be around longer than the original hardware. I don't know how far that stretches in practice.