After a virus attack on my computer on 1st May 2011, I had a computer that on booting up gave me a blank blue screen. It had a Vista OS that was attacked when I used a programme that shielded my identity and my ISP. AVG the anti-virus shield that I was using was temporally disabled by this programme and thus the attack by malware and other viruses. One of the malware was an anti-virus programme that asked for US$50 for virus and malware removal. Rather than pay this amount (which I felt had no guarantees, I decided to reformat reinstall the OS.)
Reformating and reinstalling Vista could not be done because I had no installation disks. I also did not make a recovery disk.
Since this was a six-year-old computer, I decided to use XP as the replacement OS. I had several several XP installation disks and thought at least one would work.
However all the XP installation disks I had would not copy into the computer several essential XP files during installation. I gathered that there were some hidden Vista OS files on the hard drive that was preventing it from being overwritten. The only way to get rid of these Vista files was to reformat the hard drive, but I did not utility disks to do this.
Doggedly I tried more than one XP installation disk but all behaved similarly, they refused to copy the several essential files during installation.
Then I decided to use a Windows 7 pre release disk which was given free with PC Users Magazine from Australia. This disk was a full version, given before the official release of Windows 7, for users to try out the then new OS, but it had a limited life and would not work beyond a certain date after the official release for sale of Windows 7. Well, the disk did install a workable OS; there was none of the problem of not being able to copy into the hard drive essential files as the XP installation disks had.
I changed the date of my computer to a date when this trial version of Windows 7 was valid and did the installation. When the installation asked for a product key, I gave none. I was surprised that I was required to give a product key, since originally, this version of Windows 7 was meant for a trial period and I thought it would be disabled after the period had lapsed and so no product key was required. Apparently, this was not the case and this disk actually contained a genuine, complete installation of Windows 7. What luck.
Although I did not have a product key, and the legitimate copy was not activated, the non-activated copy still worked. After this I changed the date to the present, and ignored all the messages that proclaimed that the copy of the OS I was using was not genuine. (This message appears just after startup).
So now I have a working Windows 7, which is "not genuine."
I remember vaguely, that once I tried "upgrading" my Vista computer using this same disk but unsuccessfully. The upgrading attempt took place while Vista was the OS. I think I was successful this time because the Vista OS had been completely wiped out by the virus and booting had to be done via CD/DVD.