I do not know if you would have a problem with it being a US copy. If it is a full version and it was XP we were talking about then I would be sure it would install ok. But with Vista a lot of people are having problems. Some find it installs perfectly and some are finding it won't. I do not know if there is a difference between the US Vista and the UK Vista, there wasn't with XP but with Vista I just don't know as they've changed a lot of things, upgrades for example. You used to be able to do a clean install with an upgrade disk and just put in your original operating system disk so the program could check that you had a legal copy of windows. Thats changed now. You need the original copy of windows already installed on the PC and it needs to be authenticated so now you cannot do a clean install with Vista.