Firefox 1.5.x for Windows user interface imitates the default Windows XP Luna theme since September 7th, 2005, unlike the 1.0.x releases. This means the menus look more like other applications on the default Windows XP theme, but they look out of place on other Windows XP themes, and on Windows 2000, 98, ME. This page explains how you can change your menus back to how they looked on 1.0.x releases