vista & xp in dual boot, when change order both os wont start

Hi Olan, welcome to NST
look in the wiki, and you'll find the HAL error means boot.ini is pointing to the wrong place.
You don't say what you mean by "change order". Have you reinstalled both OSs?
If you install XP after Vista, it will overwrite Vista's bootloader, and you'll need to boot the Vista DVD and "repair startup".
Point rdisk and partition in boot.ini to the correct location and XP should boot.
Give us a bit more detail about what exactly you did, and we'll help you fix Vista too.