To: ILCUL8R who wrote (74228 ) 2/22/2011 8:53:44 AM From: PMS Witch 1 Recommendation Read Replies (2) | Respond to of 110626 The retail Windows licenses are valid forever, but on only one machine at a time. You can install your retail Windows on replacement systems, but you must remove that Windows operating system from your old system. As a general rule, with OEM Windows, when the motherboard dies, the Windows license dies too. (Unless the motherboard is replaced by one that's identical: manufacturer, model...) This licensing policy applies to installing Windows. If one copies the contents of their disk to another machine, it depends: If they're quite similar, Windows will adapt to the new machine, but if they're too different, a new installation is needed. Running and needing activation are separate issues. Best case: runs OK without new activation. Worst case: needs both installation and activation. I'm unaware of any way to determine if a Windows system will run on another computer other than by experiment. Cheers, PW. P.S. In my recent messages, I was dealing with complying with the User agreement with Microsoft, and outlining what's needed to stay within the bounds of that agreement. The limits I mentioned were contractual, and NOT imposed on users by the technology. Example: It's easy to forget to remove Windows from an old system. If you don't, the old machine will still run OK, but it won't have a valid license. P.P.S. On another topic. . . I built my system inside an Antec case using a Corsair power supply. I wasn't happy with the space alloted to the PSU, thinking that airflow may be compromised. The solution was simple: I mounted the PSU upside-down. Oriented this way, the PSU fans face a much more open space.