As you said above the Yahoo!Toolbar is the only way to get tabs in ie6 as far as I know. I am also a AVID Firefox user on both my windows and linux boxes. Nothing is better and with the theme and plug-in extensions you can very quickly and easily make it your own.
If you want a great email client try the Mozilla Thunderbird. I use the Lightening extension for calendar and the minimize to tray extension to keep Thunderbird off my desktop and out of my taskbar but yet it still runs, checks your mail for you and notifies you every time it receives new mail. It has preset options for Gmail and does a multitude of tasks.
Mozilla is clearly the way... Trully safer and easier than any other browser I have tried.
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