boot.ini is the configuration file used during the NT boot process. The following is a sample boot.ini entry taken from the third partition on the first hard disk -
If the Windows XP files have been copied from a partition other than the first partition on a hard disk boot.ini will need to be edited. The only part of the file that needs to be edited is the ARC path section multi(X)disk(Y)rdisk(Z)partition(W) (where X, Y, Z and W are numeric values). For a detailed explanation of ARC paths see here.
The disk image containing the Windows XP installation will be mapped as device (hd0). At present if a hard disk image (containing a MBR and one or more partitions) is mapped then the installation will only boot from the first partition in the image file. The entries must use the following arcpath multi(0)disk(0)rdisk(0)partition(1). E.g. -