I have a strong Linux background so i'll answer in linux-way.
you may boot your system with a linux rescue livecd and perform my suggestions.
the answer assume certain unix knowledge, but just comment and i'll clarify.
- you may simply use the 'dd' tool to make copy of your windows XP installation at block level
for example:
dd if=/dev/sda of=/dev/sdb # backup the entire disk, given /dev/sda being the xp install,
and /dev/sdb being the fresh hard drive.
or copy only the concerning partition if=/dev/sda1
*note if you replace of= with a file name instead of hard drive path, it would write disk image into file.
to erase the MBR, you may use dd also
$ dd if=/dev/zero of=/dev/sda bs=512 count=1 # delete the entire MBR (including bootloader and partition table)
$ dd if=/dev/zero of=/dev/sda bs=446 count=1 # delete only the bootloader