At MIX 10 Microsoft released a Platform Preview ^[1] version of Internet Explorer’s latest version. The browser shows a lot of promise with a high ACID3 score compared to previous versions and that shown at PDC09, support for CSS 3, HTML 5 and Hardware Acceleration. The FAQ page ^[2] of the the IE9 Platform Preview has the following:

Q. Does Platform Preview run on Windows XP?

A. No. Internet Explorer 9′s GPU-powered graphics take advantage of new technologies available in Windows 7 ^[3] and back-ported only to Windows Vista. These technologies depend on advancements in the display driver model introduced first in Windows Vista.

According to an interview on in a QnA with the press ^[4] Dean Hachamovitch confirmed that Internet Explorer Platform Preview only supports Vista SP2 and above, which is effectively Vista SP2 and Windows 7 ^[3] RTM. The final versions of Internet Explorer 9 will not be supporting anything below Vista SP2 as well. The reason as stated is the GPU powered hardware acceleration that IE9 uses for a rich graphics experience.