the difference between XP and Windows 8 may be greater than the differences between XP and a typical CentOS installation It's a matter of opinion I suppose, bu

the difference between XP and Windows 8 may be greater than the differences between XP and a typical CentOS installation It's a matter of opinion I suppose, but I'm strongly inclined to disagree with this. Unless we're just talking about "where the equivalent to the 'Start' button is", or other very superficial things. Even in exceptional cases, such as users whose entire interaction with the OS is launching a web browser (and I expect this is far rarer than most people think because they forget about how often those people end up needing to print, or save off a set of PDFs, or a million other minor but common tasks), I'd still expect XP->CentOS to be at best equivalent in retraining cost compared to XP->Windows 8.