I would say ten would be the answer
The primary function of a fan in a computer system is to cool down the internal components and prevent overheating. Fanless computers use alternative cooling methods and lower-powered components that give off less heat. As a result, these machines are quieter during operation, use less energy and are often more compact than fan-based computers. These advantages are particularly important in business settings.
Choose Start→All Programs→Windows Virtual PC and then select Virtual Machines. Double click the new machine. Your new virtual machine will open onto your desktop. Once it's open, you can install any operating system you want.
