Windows update fails in Windows 8 x64 bit Professional Release Version

I have Windows 8 RTM installed in my computer which of 64-bit version. I want to convert this RTM version in retail version to get the Windows 8 Pro in my computer. I have purchased Windows 8 RTM from legal source and even paid for it. I even have the product key along with it. But whenever I try to get the retail version of Windows 8, the process fails. Can someone tell me why this is happening?

Actually the retail version of Windows 8 is not yet released. It is scheduled to be released on 26th October 2012. Till then you will have to use Windows 8 RTM only. It is good that you have the product key of Windows 8 with you and you can use it on the day the retail version is released. On the day of release or any day after that, to activate the Windows 8 retail version, you will need to go in Run, which is by pressing ‘Windows + R’. Then here you will have to type, slui.exe 3 and press Ok button. Now you will find the option to insert the 25 digit product key. After inserting the product key, you will find the product key being processed online and then a success message.

Another method to activate the Windows 8 retail version is by going in the Elevated Command Prompt and typing the following command
slmgr.vbs /ipk #####-#####-#####-#####-#####.
Here in this command, replace the ’#’ formation with the product key that you have got and press Enter. This will give you a success message and will activate the Windows 8 retail version in your system.

I think this whole process of going in the Elevated Command Prompt and running a command or going in the Run and doing all the steps is too hard for understanding for people from non-technical background. I think developers should make some provision for the activation on their website. I mean a small application or maybe online activation would be helpful. Also Windows 8 is so different from Windows XP and Windows 7, I think an online solution for activation will be best.