I have 4 32 bit laptops. All 3 have the same OS and the same Valid key when I updated from home basic (4th) I entered the key and it said this is already in use?
For Operating Systems it is one system = one key. Usage of the same key on multiple systems is only allowed for e.g. Office 2007 (maximum 3) or some OEM products like Security suites (usually also max.3).