For MASTER BOOT RECORD - from a DOS prompt type fdisk /mbr
Typical Boot.ini file:
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINNT
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINNT="Microsoft Windows 2000 Professional" /fastdetect
Remember to change the Attributes of the file as it is READ ONLY and be sure to set it back when saving.