The disk says, "Windows 7 Upgrade Option.. Vista Business to Win 7 Pro". I wanted to know whether (a) Vista had to be installed and this disk was to upgrade and existing installation, and (b) it had to be activated with Microsoft. 1. Thankfully, Vista does NOT have to be previously installed. In fact, no verification of Vista in any form is asked for in the installation process. That is, it does a "fresh install" as though it were a retail version. (It may in fact be a retail version and work on any computer... but I don't have another brand of PC to try an installation.) 2. It does require activation after 30 days, but I did not activate it. Knowing how Dell does their OEM OS disks (if that's what this is), suggest this one be used on a computer which is 3 years old or newer... Has a COA and key code. Goes for $139 at Newegg. Free shipping, of course. PM if interested.