You can put it on your notebook - however it has already been activated on the Slimline so there's a good chance that when online activation is attempted the Microsoft server will compare the two activation strings (which include the Activation Key plus the hardware details that Windows is installed on) and spot that the same key has been used on two different machines. Because it's an OEM activation code and so tied to the machine originally installed on this should mean you can't use online activation & will be asked to phone Microsoft to activate.
