You can improve your booting time of windows xp just by using startup manager.
the logon screen appears
Boot.ini,boot.exe,ntldr
The following booting files are required to start Windows XP: NTLDR, Boot.ini, and Ntdetect.com. The following files are optional when starting Windows XP: Ntbootdd.sys and Bootsect.dos. The following files are required to start Windows 7/Vista: Bootmgr (Windows Boot Manager) and BCD (Boot Configuration Data).
Dual booting means two operating system installed on PC. for example you install windows xp and windows vista at the same time. or windows xp and Linux on same PC. Dual booting is only a term you can install more than one operating system on one PC. for example you can install 10 windows xp copies on your 10 drives.
the three files in booting files in windows xp boot.ini ntldr and ntdetect.com
Key combination [Windows+L] locks Windows XP.
Yes. There is a process called Dual Booting, but it requires two hard drives. Just search for "how to dual boot windows vista and windows XP?".
Key combination [Windows+L] locks Windows XP.
Because windows 7 has stablity updates the same as windows vista dose, windows xp uses unsupported service packs. as service pack 3 is now out.
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Windows XP does not have 'proper' dos, but it does have a command prompt which is a lot like dos. You can access a DOS-like command prompt before booting Windows XP by first restarting your computer and before the Windows XP loading screen appears, repeatedly hit the 'F8' key on your keyboard. This will give you boot up options. One of them will be 'Safe Mode with Command Prompt'. This is the same command prompt that would appear if you hit [Windows]+[R] key in Windows and typed 'cmd' and then hit enter.