the first thing you need to do is go to Start>Control Panel>System>on the left side click on System Protection, near the bottom of the next box select Create, and create a restore point( can you believe that the installer doesn't by itself ! ) then go to >Programs and Features> Look on the left side and select View Installed Updates look closly for KB 2259539( some people refer to it as the SP1 upgrade, IE9 will not install if it's there and you could end up with a few problems like me ), if you got it Uninstall it then run the IE9 installer, looks like a model T, talk about plain Jane, down right ugly, right click on the header bar to activate the menu's, in my case IE9 didn't work, wouldn't open any internet pages, not even MSFT's, uninstalled it, so good luck