I recently wanted to combine two machines - one was a linux box, the other ran Win2k. I decided to just stick both HDDs into one machine. Windows obviously wouldn't cope if the hardware was altered beneath it, so I simply put the old linux disk in as slave to the Windows primary master.
LILO can't boot Win2k, or at least Win2k won't boot from LILO, so I let the Windows boot
loader do the work. Using Knoppix, I used LILO to write
to /dev/hdb1 (linux /boot partition). I then used dd to take the boot sector from this partiton
and save it to a floppy.
dd if=/dev/hdb1 of=/tmp/bootsect.lnx bs=512 count=1
I then rebooted the machine into Windows, copied to boot sector file into c:\ and added a
line to c:\boot.ini
Job done. When the machine boots, the Windows boot loader gives the option of booting into
Linux, and when selected, this runs LILO.