Hello, You can try one thing.First use dd command in linux and create a backup of your current MBR on a floppy/CD,atleast it allows you to boot into some OSs if not all.Put that backup(which should be a single file of 512 bytes) on hda1,so that you can use it with your boot.ini file later. Then you can boot into DOS using a startup floppy or CD and revert the MBR using 'fdisk /mbr'.I think this will bring back the contents of the MBR (most probably the NTLDR) which were there before GRUB overwrote ur MBR.Then you will be able to boot into XP,2K,98 as before.After getting NTLDR alright,then just add an entry to your boot.ini with the backup file as the target..If it works well then you'll be able to go into GRUB thru the Windows boot menu. *The crucial thing is to use the dd command neatly. I think it will be 'dd if=/dev/hda1 of=/mnt/win_c/backup.mbr bs=512 count=1' assuming that hda1 is mounted as win_c Get it verified.*
Hope this helps.