Good Day everyone, I have a question to ask, I'm not really good in technical in computing. Hope all the expertise can help me on this. I have 3 Dell PC, 2 old, 1 new. The newly PC I purchase is come with Windows 7 Professional dvd and pre-activated by Dell. But when I use the Disc to install at another two older machines, they are require for activation. But I tried install into the new machine, it doesn't require for activation. Actually I would like to check out, how is Dell recovery disc works? Are they detect the BIOS to determine the machine type? How do I overcome this for my another 2 old machines, so I doesn't require for activation? Thank you.