If you’re already using any of the 1.5 versions of Firefox then you can either wait for it to update in the background, unless you’ve disabled that ability or you could click the “Help” menu and then “Check for Updates”.
For those of you still using Internet Explorer… [smack upside the head] WHAT THE HELL ARE YOU THINKING? STOP IT. and if the abundance of capital letters in those last two sentences don’t turn you around, perhaps the article I link to below will be enough.
Automated update to streamline product upgrades. Notification of an update is more prominent, and updates to Firefox may now be half a megabyte or smaller. Updating extensions has also improved.
Faster browser navigation with improvements to back and forward button performance.
Drag and drop reordering for browser tabs.
Improvements to popup blocking.
Clear Private Data feature provides an easy way to quickly remove personal data through a menu item or keyboard shortcut.
Answers.com is added to the search engine list.
Improvements to product usability including descriptive error pages, redesigned options menu, RSS discovery, and “Safe Mode” experience.
Better accessibility including support for DHTML accessibility and assistive technologies such as the Window-Eyes 5.5 beta screen reader for Microsoft Windows. Screen readers read aloud all available information in applications and documents or show the information on a Braille display, enabling blind and visually impaired users to use equivalent software functionality as their sighted peers.
Report a broken Web site wizard to report Web sites that are not working in Firefox.
Better support for Mac OS X (10.2 and greater) including profile migration from Safari and Mac Internet Explorer.