If you're the type to live life on the edge, Mozilla has just posted the Firefox 4 Beta 1 candidate build. The early version has many of the upcoming features we've heard about, including a new menu button that aggregates the most frequently used browser menu options, native compatibility with Windows Vista and 7's Aero Glass interface, a customizable tab bar, and a bookmarks button.

Firefox 4 Beta 1 candidate also relocates the default position of tabs to above the address bar a move many users claim Mozilla is copying from Chrome and Opera. The organization wants you to know that isn't the case. To set the record straight, Mozilla has released a video explaining the thought behind shifting the tabs northward, and the reasoning seems logical enough.

ConceivablyTech has already tested the early build with SunSpider, and although its performance is an improvement over Firefox 3.6.6, Firefox 4 Beta 1 still trails behind Chrome, Opera, Safari, and even IE9 PP3. You can download beta candidate here, but we wouldn't recommend running it as your primary browser just yet. We haven't seen a due date for the official first beta release, but it shouldn't be far off.