OS Platform Statistics:
Windows XP => 69.8%
Windows Vista => 16.5%
Windows 2000 => 1.6%
Windows 2003 => 1.6%
Linux => 3.9%
Mac => 5.8%
Browsers Statistics:
IE8 (Beta 2)=> 0.6%
IE7 => 25.7%
E6 => 18.5%
Firefox => 45.4%
Chrome => 3.8%
Safari => 2.9%
Opera => 2.3%
Source: http://www.w3schools.com/