opera browser

I have a client that needs to play AVI video files, in a web browser, preferably though the QuickTime player. (If not QT, then some other player where the user can examine the videos frame-by-frame, that is readily available.) And, theoretically, they must be AVIs, since they are the primary...

What's the best substitute for IE and why? I have Firefox on my laptop but that's a memory hog (or did they fix it)? I've had Safari 4 which made sites look slightly different. Is Safari 5 better? I've had Opera way back when, and I liked the mouse gestures, but as far as I know Opera isn't...