Hrm. I tried double-clicking an SWF-file on Windows 2000, and it completely locked up Firefox 0.8. I got about 30 to 40 child processes running at the same time. The machine didn't crash (good), but so far the only way to look at these Shockwave thingies is by starting the browser first and then open them from within there. Plus any non-IE browser I've used always displays annopying clipping behaviour when playing said files, unless I enter full-screen mode with [F11]. I'm not sure whose fault that is, though. I tend to blame Macromedia.
But it's a decent browser. It will be great when it has Mozilla's AutoComplete options for the Location Toolbar. That is about the only feature I really, really miss.