since when was opera stable on windows?
I use both Firefox and Opera 10.6 on Windows 7 (I use both at the same time, lots of tabs - log-in sites go in Firefox, Opera for general browsing).
Opera 10.6 is the first version of Opera I have ever used. I dislike the lack of customization, which is why I still use Firefox. But Opera has the basic needs right out of the box - adblocker with custom script capability, pop-up block, awesome javascript engine, great flash compatibility, and very stable memory management. I keep 50 tabs open quite often, rarely ever have to close Opera.
Firefox likes to eat memory if you let it stay open constantly with many tabs.
I might have to check out IE9, tried Chrome for awhile but as a secondary browser, I like Opera much better. It might be time to see if IE9 can make the comeback and replace one of my browsers. I might wait awhile to see some detailed reviews of the underlying software, like Java and HTML5. Also, plug-in compatibility, and chiefly, security and how well security tools - like ad-block and script-blocking - actually function under regular use.