For security reasons, I would not recommend using any version of Explorer other than version 9. If you are running Windows XP operating system, the highest Explorer version you can upgrade to is Internet Explorer 8, which was released in 2009. Microsoft last released a cumulative security update about a year ago for Explorer 8 but due to it's age, it still has various security deficiencies that were corrected in version 9. If you are running Vista or Widows 7 operating systems, you can upgrade to Explorer 9 .
Otherwise, if you have an XP operating system, make sure you run Automatic Update (it's in your Control Panel) and you should be using Firefox (
www.mozilla.org ) or Chrome by Google, since those browsers are updated with the most current security fixes and can run on XP.