The new interface is only default on Windows Vista and Windows 7. To get it on Windows XP you need to hide the menu bar. To do that in the View menu select Toolbars, then click on the "Menu Bar" entry.

If you need access to the menus you can press either Alt or F10 to temporarily display them.

Thanks! Is there any central info page about what's different on Win XP? There are a some other things I can't seem to find. For example, when right-clicking on a tab I don't have a "Move to Group" option; is Panorama implemented on XP?

Panorama is implemented, but hidden by default.

Use keyboard shortcut Control+Shift+E to start using tab groups (panorama). Drag one of the tabs onto a blank part of the screen to create a new tab group. After you have used tab groups the "Move to group" menu item will appear and an icon to launch tab groups will be added to the tab bar.

For more details on using them see https://support.mozilla.com/en-US/kb/what-are-tab-groups

Hmm. Okay, thanks. That is definitely something I never would have found. I have the distinct feeling there must be more new features I'm not seeing in XP. Is there no central help page documenting what these might be and how to enable them? (Prior to posting here, my searches didn't turn up anything.)

The panorama thing is not specific to XP, that is for all OS's. Mozilla did that partially to avoid people accidentally launching it and not knowing what had happened, and also due to some underlying issues that still need to be sorted out with panorama, some involving memory management.

Thanks Tony!!! Just what I needed.

Thanks for the info on how to turn off the old menus!

However, now I have the tabs on the same row as the Firefox button. All the demos and screenshots show the tabs just below the Firefox button.

As I tend to run a lot of tabs at once, that extra bit of real estate is greatly desired (I hate scrolling tabs!). ;) I can't find a setting, however, and it is definitely different than the "tabs on top" setting.

Any ideas?

ackthbbft, when the Firefox window is maximized, tabs are on the same row as the Firefox button, they are below it when the Window is not maximized. I have a workaround for you, if you use the Firefox UI Fixer add-on, it changes the Firefox button to a smaller button containing the Firefox icon, and allows you to move it elsewhere.

https://addons.mozilla.org/firefox/addon/firefox-4-ui-fixer/

Wow, do I feel stoopid! Thanks yet again, TonyE! I'll also check out that addon.