I've ordered a bunch of new components which will be arriving today. My retail copy of Win 7 Pro is currently installed on my existing machine, which my young sister has been using whilst I've been overseas for the past year. I want that copy for my new machine, and I've ordered an OEM x64 Home Premium for that machine to continue functioning. However, she's in the middle of A-level exams at the moment, so I need to keep disruption to a minimum. Can I install my retail copy on my new machine without removing it from my existing one? Just until next week when she finishes her exams, at which point I'll do a clean format... Will it work?