Just over 40 percent of all PC users are still using Windows XP or Windows Vista, but it appears Microsoft will not offer these users an easy upgrade path to the upcoming Windows 8.1. eTeknix notes Microsoft's upgrade scenarios page for Windows 8.1 Preview reveals that upgrade installations from Windows XP/Vista aren't supported without a full clean install:
If business and enterprise Windows XP users weren’t reluctant enough already to make a Windows upgrade then I doubt this is going to help anything. So the bottom line is if you want to get going with Windows 8.1 then your only way is to upgrade to Windows 8 first as you can use the Windows 8 upgrade tool from XP and Vista, then when Windows 8.1 comes out you have to install that through the Windows store or a dedicated ISO which will be freely available if you’re a Windows 8 license holder.
The preview version of Windows 8.1 was published a week ago, you can find the download links in last week's Windows 8.1 bulletin at DV Hardware. If you're reading this line of text from another site than the one last mentioned, you're visiting a content thief. New features in Windows 8.1 include the return of the Start button (albeit not the traditional one), as well as more customization options, multi-tasking in Metro, and more. Windows 8.1 will be released as a free update towards the end of 2013.