Dual booting Windows XP / Vista when Windows XP Installed First [Guide, Walkthrough] Introduction: This is a guide to help you dual boot Windows when Windows Vista was installed first and want to install Windows XP as a secondary Operating System. I have done this method myself and it has worked well. Guide: Firstly you will need to install Windows XP on to a separate partition of your hard drive. This is a fairly easy thing to do as you can use a partition program to separate your hard drive. After this you will need to install windows on the extra partition you have made. Then you will only be able to boot in to Windows XP but you will see the partition of windows vista in my computer. Now you will need to place the Windows Vista disc in the drive and boot of of this. Once it has booted you will get this: You will need to click on the “repair your computer” link then you will encounter this window: Make sure that Windows Vista is selected and then press next. This window should appear: To get Windows Vista back to boot from start up you will need to click on command prompt and type these two simple lines in to the window that appears: Bootrec.exe /fixMBR Bootrec.exe /fixBoot You will now need to exit the command prompt and restart your computer. You will now boot in to Windows Vista. Now to get your boot screen with both Windows Vista and Windows XP. You can do this by using programs such as easyBCD and others. I tried these with no success and they just got annoying so I did it manually by using the command prompt. This is how to change your boot.ini in command prompt as in Vista the boot.ini is not editable directly. Firstly you will need to open command prompt will admin privileges: And then you will need to type these commands in to the command prompt directly: bcdedit –set {ntldr} device partition=C: bcdedit –set {ntldr} path \ntldr bcdedit –displayorder {ntldr} –addlast bcdedit -set {ntldr} description "Microsoft Windows XP" Before: After: You have now added Windows XP to your boot loader and will display this next time you turn your computer on: Vista will be the default boot, so if left Vista will boot automatically. Any questions, feel free to reply.