Before you go and buy the Windows 8 upgrade or the DVD from retail store, it is best that you run the Windows 8 Upgrade Assistant from Microsoft.
Currently, I am on Windows 7 Ultimate. I ran through the Windows Upgrade assistant and was surprise to see the possible issues that I would face.
I am surprised that Windows Media Centre isn’t preinstall and I need an application to play DVD.
I did a check on the FAQ
Is Windows Media Center included in my upgrade?
No. If you want to install Windows Media Center, you need to buy the Windows 8 Media Center Pack after you upgrade to Windows 8. For more info, see the Add features webpage.
If you don’t have a third-party app that plays DVDs, or if you currently rely on Windows Media Player for DVD playback, you’ll need to download and install a third-party app or install Windows Media Center to play DVDs. If you use Windows Media Center on Windows 7 and are upgrading to Windows 8, for a limited time you can get the Windows 8 Media Center Pack for free.
Other issues are that my processor does not support NX and secure boot isn’t compatible with my PC’s BIOS.
To my surprise, it prompts that my screen resolution isn’t 1024×768. This is strange as I am running at 1280×720 wide screen.
Although Windows 8 upgrade promises upgrade paths for Windows XP users. It seems to cut off all support for Office 2003. My copy of Office 2003 professional has to go into history as it won’t run on it.
The good news is that most of my applications like adobe reader, Auslogics Disk Defrag, Epson Scan, Paint.Net, Tweetdeck, Quicktime, Skype, utorrent and even the Intel HD graphics drivers are compatible and it will run corectly under Windows 8.
So, it is better to run the Windows 8 Upgrade Assistant before you upgrade.