If you’re one of the few Firefox users still on Windows 2000 or still using Windows XP without Service Pack 2 or later, Firefox is going to have to say goodbye. Yesterday, Mozilla’s Asa Dotzler announced that Firefox team is moving to a newer version of the Visual Studio toolchain. Once Mozilla moves to Visual Studio 2010, they won’t be able to build for Windows 2000, XP RTM or SP1.

Dotzler says that the team has held off “for a number of years” to preserve support for Windows 2000, Windows XP Release to Manufacturing (RTM), and Windows XP SP1. Unfortunately, that comes at a price. “Our developers have not been able to take advantage of new compiler features and have had to struggle to keep valuable optimizations from breaking – including having had to back out and ultimately delay some important new features like SPDY.”
Finally, Mozilla is saying a fond farewell to the 0.4% of Windows users that are still on those really old releases. But there’s still time. Says Dotzler, “Next Tuesday or Wednesday, after Firefox 12 moves to Aurora, the Mozilla Release Engineering team will begin upgrading our Windows build systems to Visual Studio 2010.
It is, of course, worth noting that Mozilla has supported Windows 2000 and XP with new browser versions longer than Microsoft itself. Internet Explorer 8 requires XP with SP2 or higher, and does not support Windows 2000 at all. Internet Explorer 9 requires Windows Vista or later. Mozilla has supported a tiny fraction of its user base with legacy systems far, far longer than most projects or companies would have done.
If you’re on one of the old XP releases, you can still upgrade with Microsoft’s free service packs. For larger organizations, there’s the Extended Support Release, which will provide an extra six months or so before the older versions become unsupported.