The orange Firefox menu button is hidden by default on Windows XP.
You see the orange (on Linux gray) Firefox button if the Menu Bar is hidden, so you need to hide the Menu bar to get the new appearance.
If you need to access the hidden Menu bar then press F10 or hold down the Alt key to make the Menu Bar appear temporarily.
You can place the Tab Bar on top.

• View > Toolbars : [ ] Menu Bar
• View > Toolbars : [X] Tabs on Top

Thank you Cor-el: very helpful indeed. That's up and running on my PC.

But ... I've now downloaded Firefox for use on a laptop, using Windows 7, but when I double-click on the Firefox desktop icon to connect to the internet, I get a fleeting glimpse of the Firefox home page and the Firefox menu button before the Google home page appears and I can see no obvious way of changing that so that the same Firefox home page appears on my laptop as on my PC. I hope this doesn't seem too daft.

Simon

Firefox 4 uses a new build-in default home page call about:home (about: is a special protocol to access some build-in pages).

You can set the home to the same page as on the other computer via Firefox or Tools > Options > General.

See:

• How to set the home page