Hi all, I am new to windows 7 and I need some expert knowledge on installing windows 7 on a HP Pavilion PC currently running genuine Windows Vista brought from new 3 years ago. I have checked with microsofts Windows 7 upgrade advisor and it reports back as 100% ok to run on my machine. I have 2 copies of windows 7 (Retail & OEM) downloaded from elsewhere on the net, but I am not sure about which copy I can use and what about COA Keys & Activation !. Can anybody give me some info on this subject and possibly which direction to take?. Kindest regards in advance.