Have you tried dual booting with Windows Vista and Windows XP?

Well, I sat down earlier to set up a machine to dual boot with Windows Vista and Windows XP, which proved to be a little interesting. I noticed when I installed Windows Vista on a separate partition to Windows XP, I ended up with 2 boot managers. Not ideal I thought. A little digging found the following post: http://chris123nt.com/guides/Beta1_5112/#boot

Where the author suggests copying the boot loader (winload.exe) from the Vista to the XP partitions, then editing the Boot.ini file using the /USENEWLOADER switch to force a single boot loader…

You need to copy the winload.exe file from the Windows Vista Drive; “\windows\system32\winload.exe” to the Windows XP partition “\windows\system32” directory, then edit your boot.ini file.

My Boot.ini file started off life like this:

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect /NoExecute=OptIn
multi(0)disk(0)rdisk(0)partition(2)WINDOWS="Microsoft Windows Longhorn" /NOEXECUTE=ALWAYSOFF /FASTDETECT /USENEWLOADER

Adding the /USENEWLOADER switch for the Windows XP configuration gave me:

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect /NoExecute=OptIn /USENEWLOADER
multi(0)disk(0)rdisk(0)partition(2)WINDOWS="Microsoft Windows Longhorn" /NOEXECUTE=ALWAYSOFF /FASTDETECT /USENEWLOADER

..and all was well.

Enjoy!