Do not download IE9 from third-party "download manager" sites (e.g., Download.com, Softonic, oldversion.com). They often bundle adware, spyware, or outdated unsigned installers.
Why? Because most plugins and ActiveX controls at the time (such as Adobe Flash Player, Java, and various banking security applets) were only compatible with 32-bit browsers. If you ran the 64-bit version of IE9, you would often find that your favorite websites wouldn't load video or interactive content because the plugins simply didn't exist yet. Download Internet Explorer 9 -32 bits- Final -3...
only if:
Before downloading, understand the legitimate use cases: Do not download IE9 from third-party "download manager"