Back in July we wrote that support for Windows 2000 and XP SP1 would be ending with the Thunderbird 8 release (November 8, 2011) due to Mozilla moving to C++ 2010 compiler. Thunderbird 10 was released on January 31st and still supports Windows 2000 as well as all versions of Windows XP.
Bug 563318 (switch Firefox trunk builds to use Visual C++ 2010) has had landed on the Firefox 13 Nightly builds (has been temporarily backed out to address some crash issues). This also means the Comm-Central (Thunderbird Daily) channel would have had the same update. So those who are wanting to use the Thunderbird 13 Daily builds will need to be running Windows XP with SP2. Windows 2000 users will need to find a new email client. Thunderbird 13 will be released on June 5th, 2012 which means that Thunderbird 12 scheduled for release on April 24th, 2012 will be the last Thunderbird version to support the older versions of Windows (2000 and XP SP1). Important: Because Thunderbird 10.0.0 ESR (released January 31st) is based off of Thunderbird 10, it will continue to support the older versions of Windows until the next release of ESR 17 (based off of Thunderbird 17) on November 20th, 2012 (though support of ESR 10.0.x will continue through February 2013)
It’s a quite logical step, since Microsoft is coming with W8. XP is ending it’s era.