In earlier versions of Windows,eg:windows xp, boot.ini was a system file that contained information about the Windows operating systems installed on a computer. This information was displayed during the startup process when you turned on your computer. It was most useful in multiboot configurations, or for advanced users or administrators who needed to customize how Windows started.
In this version of Windows, the boot.ini file has been replaced with Boot Configuration Data (BCD). This file is more versatile than boot.ini, and it can apply to computer platforms that use means other than basic input/output system (BIOS) to start the computer.
If you need to make changes to BCD, such as removing entries from the list of displayed operating systems, use the command-line tool Bcdedit, an advanced tool intended for administrators.
If install more than 1 systems on your computer,you can change which OS been opened by default and how long to display the list of operating systems.Below is a simple guide about how to do it.
1.Go to Control Panel and click System
2.In the left pane, click Advanced system settings
3.Click the Advanced tab, and then, under Startup and Recovery, click Settings.
4.Under System startup, choose a default operating system and the amount of time to display the list of operating systems, click OK, and then click OK again.