
Microsoft has released final version of Internet Explorer 9 for 32 Bit and 64 Bit Windows PCs. IE9 can be installed on any computer running Windows 7 or Windows Vista Service Pack 2. As per IE9 system requirements, it will not be installed on Windows XP. So, XP users are out of luck.
As for Windows Vista users, you need to have Service Pack 2 installed in order to install IE9. Windows 7 users can install IE9, but it’s recommended to have Windows 7 SP1 installed. Here are download links:
Windows 7 x86: IE9-Windows7-x86-enu.exe
Windows 7 x64: IE9-Windows7-x64-enu.exe
Windows Vista x86: IE9-WindowsVista-x86-enu.exe
Windows Vista x64: IE9-WindowsVista-x64-enu.exe
Windows XP x86 & x64: http://www.google.com/chrome 
Enjoy Beauty of the Web.