Hey, I've never once, ever, reformatted my computer. I've had a variety of issues with my computer for /years/, windows installer.exe being unusable being the worst of the worst. I've always told people who tell me to reformat that it's just not an option as I don't have the original disks and I can't afford a new OS. Well. I've just found the original disks. In a disk holder in my attic that I thought was completely empty.. I've acquired a 250gb hard drive from my father to back up with. My questions are: 1: How do I go about reformatting? (I know vaguely, but yeah) 2: Will I be required to enter some sort of product key, if so, where do I find it? (Is it the "Product ID" in computer properties?) 3: What else should I backup, besides the things I'm aware I want to keep, (music, games etc). Like, is there anything that most people forget to backup and soon regret after they reformat their PC? Quick replies would be appreciated as I'm really looking forward to an error-free PC! Thanks in advance.