Ok, so lets start from square one.A little over a year ago i bought a acer computer with a quadcore in it and a 1tb westerndigital hdd.I eventually switched out the hdd to another computer with is the one i have now 100$ custom except my os . i have the serial key for my operating system. im hoping to be able to use that serial key to download my os onto a flash drive so i can have a fresh install of windows because i play alot of modded games like dayz and gmod and they fill my pc up with random files i don't need also i think a new fresh install would be nice for my computer. is this possible to do? I do not have the money to buy a whole new windows 7 disk witch is why i need to be sure this will work and not be some half half thing.