Open LOGONXP File
The LOGONXP file extension is used for the Windows XP logon screen, created in LogonStudio and originally developed by Stardock Corporation, in this case, for LogonStudio.
More about LogonStudio
LogonStudio is a free program that allows users to change their logon screens in Windows 7, Vista and XP.
It comes with several login screens to choose from, along with thousands of templates that are available online from websites like WinCustomize.com.
The LOGONXP extension file saves custom logon screen settings used by LogonStudio, and can include a background image as well as custom fonts and buttons that can be applied to the Windows logon screen.