It varies a bit. If you have never installed Firefox 5 before, then in Vista and 7 you probably get the orange Firefox button (abbreviated menus) while in XP you get the classic menu bar. However, it is easy to switch between them. If you want the classic menu bar, tap the Alt key to display it and then View menu > Toolbars > ''check'' Menu Bar If you want the orange Firefox button, then View menu > Toolbars > ''uncheck'' Menu Bar The toolbars menu also is available as a pop-up when you right the classic menu bar, or a blank area of the tab bar, or various places on other toolbars. --- Other than that, the UI should look pretty much the same, setting aside those weird translucent window effects in Vista/7.

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