im thinking of adding Windows to my new pro and I cant decide whether to use win7 which I currently have on my desktop or 10 which I have on a laptop. Prefer 7 as I just feel most comfortable with it and I know the 4 old games I play on it work. Also have office 2007 so that too will save me money. My question is I see these window keys on EBay and Amazon for anywhere from about $20 to well over $150 with CD. Since I can download windows onto a flash drive already to use are these legitimate keys or a scam. I’m a believer in if it’s sounds to good to be true it probably is yet I can’t find any warnings against using them. What is the opinion here?