User interface

Windows XP features a new task-based graphical user interface. The Start menu and search capability were redesigned and many visual effects were added, including:
A translucent blue selection rectangle in Explorer
Drop shadows for icon labels on the desktop
Task-based sidebars in Explorer windows ("common tasks")
The ability to group the taskbar buttons of the windows of one application into one button
The ability to lock the taskbar and other toolbars to prevent accidental changes
The highlighting of recently added programs on the Start menu
Shadows under menus (Windows 2000 had shadows under mouse pointers, but not menus)
Windows XP analyzes the performance impact of visual effects and uses this to determine whether to enable them, so as to prevent the new functionality from consuming excessive additional processing overhead. Users can further customize these settings. Some effects, such as alpha blending (transparency and fading), are handled entirely by many newer video cards. However, if the video card is not capable of hardware alpha blending, performance can be substantially hurt and Microsoft recommends the feature should be turned off manually.Windows XP adds the ability for Windows to use "Visual Styles" to change the user interface. However, visual styles must be cryptographically signed by Microsoft to run. Luna is the name of the new visual style that ships with Windows XP, and is enabled by default for machines with more than 64 MB of RAM. Luna refers only to one particular visual style, not to all of the new user interface features of Windows XP as a whole. In order to use unsigned visual styles, many users turn to software such as TGTSoft's StyleXP or Stardock's WindowBlinds. Some users "patch" the uxtheme.dll file that restricts the ability to use visual styles, created by the general public or the user, on Windows XP.

The new start menu design in the "Royale" theme.
The default wallpaper, Bliss, is a BMP photograph of a landscape in the Napa Valley outside Napa, California, with rolling green hills and a blue sky with stratocumulus and cirrus clouds.
The Windows 2000 "classic" interface can be used instead if preferred. Several third party utilities exist that provide hundreds of different visual styles. In addition, another Microsoft-created theme, called "Royale", was included with Windows XP Media Center Edition, and was also released for other versions of Windows XP, but has since been removed from the original Microsoft New Zealand package. The Luna theme uses 4 more megabytes of RAM than the "Classic" Windows theme, so Classic can possibly improve performance on lower-end systems. A matching black theme by Zune can also be downloaded for free from the Zune website (see Energy Blue).