Dual Operating system in other words is installing two operating systems in separate partitions on the same computer. Example you can run both Windows and Linux at the same time. The only problem with this "dual booting" is that its impossible to use both the operating systems at the same time since you can boot into just one operating system at a time. The more productive way to run two operating systems today is by using some kind of virtualisation tool like VMware or VirtualBox. These softwares allow one to run one operating system inside another. For example you could run Linux inside Windows, or Windows inside Linux, and use both Microsoft Word and Xwindows at the same time. And if you have the right integration tools installed, you would also be able to cut-and paste data between the two operating systems. Unfortunately, all this comes with a slight performance loss, so having a faster processor will help.