While I had upgraded linux versions - both fedora and ubuntu in my home computers quite regularly, I had never attempted to change the Windows OS. This was because, there was no online upgrade option. Also, the operating system cost was high.
When I saw the tempting offer of a Windows 8 Pro upgrade for Rs.1999/- I could not resist. (By the way, this offer is valid till Jan 31, 2013, as I write this). I had a Windows 7 laptop and I downloaded the Windows 8 upgrade assistant. I ran this and it indicated that my laptop met the requirements for upgrade. The same tool had the user interface to buy the upgrade.
Now, what the tool did not tell me (and hence I write this) is that you need about 15 GB of disk space on your Windows partition if you want to upgrade. Considering that we accumulate files and folders to fill the disk space available, it is not easy to create such space.
You get this to know this information after you purchase the upgrade and before it starts downloading the software.
Windows 7 allows you to extend and contract partitions. However, the extension works only across contiguous partitions. This means, assuming your partitions are C, D and E in that order, you can extend C only if D is free. I learnt this the hard way. I initially moved files from C to D to free up space and later moved files from D to E since D needed to be free, if I wanted to extend C.
The tool asked me to enter your personal details and provide credit card information. Interestingly, this online purchase did not go to the 3-D Secure authentication. According to the email receipt the seller was arvato distribution GmbH - a German reseller. A product key was sent by email as well.
It then began to download 2GB worth of files. I ran the upgrade about 10.30 PM and went to sleep. When I got up in the morning, the files had downloaded and Windows was ready to upgrade.
I was quite impressed - at my internet provider (Hathway), since I could not recall such a large download, which came through uninterrupted and with no intervention. The upgrade involved was pretty smooth. A couple of questions were asked - like do you want your existing applications and settings to be retained, which you should. It also involved a number of reboots, but at the end of it, I was presented with the now popular Windows 8 start page.
One step you should do once you have your upgrade running fine is to remove the old Windows installation, since it occupies about 15 GB of disk space! I did this by following the instructions here.
We do miss the Start key, but have figured out a way to power down the laptop.