Nope im afraid not spud. It is illegal and besides probably wouldn't work. You will need another copy.
I will explain Windows Anytime Upgrade for you:
Windows Anytime Upgrade is a scheme run my Microsoft to make it easy for you to upgrade between different versions of Windows Vista. All vista discs have every version on them but your serial code only relates to one, if for example you were on Vista Home Basic and you wanted to upgrade to Home Premium you would phone Microsoft and buy a serial code and simply use that instead of having to buy a new disc. Im not sure if there are other methods other than ringing MS.
Hope that explains it for you
Chris