OK, whenever I need a new PC, I do a few hours' research on the internets, then go online and buy my parts. This includes an OEM Windows disk, which you only need to buy once. I've done this three times in the last 7 years. It's fun and saves a lot of money. So, when my parents (who are in their 60's) needed a new PC a few years ago, I offered to build one for them. I put together a decent Athlon XP 2000 system for them, enough for their needs. Unfortunately it got fried when a transformer near their house exploded, so they need a replacement. Problem is, my mom can't find her Windows disk. I have the Certificate with the license key, taped inside the PC case where I put it 3 years ago. But she can't find the actual disk that came with it. Are Windows XP disks "attached" to the key that comes with it? My mom bought the license, so even if she can't find her disk she should be entitled to have Windows XP on her new PC (and since Vista is not too far off, I hate to make her buy another XP license now). Can I use my Windows disk to install Windows on her PC and use her license key, or will this cause a rift in the time/space continuum?