Also, you should have an option to uninstall IE 9... which should automatically revert you back to IE 8... no reinstall necessary. You cannot download an IE 8 installer for Win 7 since IE 8 is what it comes with.
As for games, unless they are browser-based games, you shouldn't have any issues with IE 9 and games. I haven't come across a thing yet that IE 9 has had issues with personally. If you have ActiveX filtering enabled, you have to remember to disable it for pages that run plugins like Java or Flash.
I did try to uninstall IE9 under the advice of a friend, and she said the same thing, that it should revert back to IE8 but it never did... I cannot view certain e-bills since I installed IE9, and some parts of certain games on facebook will not load, I get an empty screen, or have to move my cursor around the screen in order for certain things to work. I will check my ActiveX filter, thanks for the tip!