Sources within Microsoft have officially confirmed that the US software giant will soon cut support for older Skype versions. The bad news for users of older Microsoft operating systems and older Skype versions is that only the latest Skype versions will be supported starting with Skype 6.14.
Microsoft has explained this harsh move with more and more important features that older Skype versions do not support. In addition to that the company has cited numerous Skype features that new versions support and old versions do not thus making communication harder and in some cases impossible. For example you can send messages to friends in offline mode, which is something that you cannot do with older Skype versions. Everyone that uses this popular messaging program is urged to update its version to the latest. There’s more though – the latest Skype versions do not support processors that lack SSE2 instructions, which might retire some old computers here and there.
This is bad news to users of older hardware and versions of Windows 2000 or earlier. At least if you use Windows XP3 or newer and have a SSE2-enabled CPU you will not have to upgrade your OS.
Source: Microsoft