Using Acronis True Image with Universal Restore from Win7, apply the XP image to a partition you create for it.
Without restarting install EasyBCD 2.0.2
to Win7, add XP by drive letter you assigned it during restore, accepting any offered boot files, let it autocomplete.
You can do all of the above from Win7, then restart to a working Dual Boot in most cases.
If this fails you can either SysPrep XP HD on its old hardware then apply the image to Win7 as above, or run a XP Repair Install on the reimaged partition if it is made available during this process: XP Repair Install - Part 1 of 2