fixboot won't solve the problem. I tried already. you need to use fixmbr to remove grub. fixmbr available for XP but not in Win NT4.
alternatively, you can use grub to help you to boot your windows by directing the GRUB to load your NTLoader.
grub> rootnoverify (hd0,0)
grub> makeactive
grub> chainloader +1
grub> boot
Assuming your Windows is in HDD 1 and partition 1.
grub is a tool helping you to choose which OS you want to load if your machine loaded with multiple OSs.