A lot of companies are still using old versions of Internet Explorer despite the security risks and lack of support for modern web applications. There are two methods of supporting both old and new.

First, from Google is Chrome Frame which … equips older versions of Internet Explorer with the speedy rendering and JavaScript engines at the heart of Chrome.

The second is the third-party IE Tab, which lets you use Chrome for most of your work and open a tab that runs IE for those webpages that won’t run on anything else.

• Google Wraps Internet Explorer in Chrome Clothing | Wired Enterprise | Wired.com.
• Google Chrome Frame 
• IE Tab