Right so in September I bought a copy of W7 but it appears I was sold a DSM copy and not a retail version. Microsoft have blocked my product ID and so I can't activate it. I had done a reinstall recently that's why I had to reactivate. It looks as if I will get my money back for it, but obviously need to replace the OS with a new copy. My question is will I be able to use the OEM version to reinstall the OS? As in when I go to advanced recovery and choose Reinstall Windows [Reqires Windows Installation Disk] will the OEM version be sufficient to work in doing the job of the reinstall? I'm asking cos my knowledge on this stuff is limited and see that the OEM is for builders and I did originally buy a custom PC without an OS but am wondering if the OEM needs to be applied to a blank system or will do the job as a reinstall? Thanks in advance to anyone who can guide me!