I thought Lilo could boot NT just fine, there may be something self inflicted here. But anyway ...
Don't do this until you understand every bit of what you have to do, or you may have to restore an image. I am also assuming that lilo has been run only the one time.
From the lilo man page...
Uninstall lilo by copying the saved boot sector
back. The '-s' and '-C' switches may be used with
this option. The device-name is optional. A time-
stamp is checked.
DON'T leave Linux after removing lilo from the mbr or Linux will be hosed, unless you're going to just remove it. If you're going to remove fdisk it out from under it's self
As su /sbin/lilo -u should restore your mbr, can't say I've ever tried it on an NT machine. NT can be a bear if it won't boot, hopefully you have a Win9x boot disk or something similar laying around. If not you may have to download one if you can't bum one from a friend if the mbr isn't restored properly. I'd have one on hand before trying this.
Verify that you have a /boot partition or directory, it don't really matter which.
You will need to modify /etc/lilo.conf before re-running lilo.
Mine's not going to be the same as yours, but it'll serve...
WARNING if your boot and root lines don't match up with the below I've made a mistake or bad assumption. Post /etc/lilo.conf and /etc/fstab and get it straightened out before attempting this.
#prompt ## comment this line out with #
boot=/dev/hda ## change this to /dev/hdb1
root=/dev/hdb1 ## verify this line
Dos stuff here, remove it.
As su run /sbin/lilo -v and watch for errors.
Make a boot disk for Linux. mkbootdisk your_kernel_version I believe for RH7.2 if not there is a gui tool, or browse the administration section of the man pages with xman looking for mkboot...
As su do dd if=/dev/hdb1 of=linux.bin bs=512 count=1
Put linux.bin on a dos floppy.
Restart the box, with luck it will boot NT. Add Linux="C:\linux.bin" in boot.ini and copy linux.bin to C:\. The next time you restart you should be able to boot linux from the nt bootloader. If not there's the floppy
If NT still won't start, boot a dos floppy and run fdisk /mbr and try again. If it still don't boot NT restore the image of C: and repeat the boot.ini tweak and linux.bin to C:\
If something don't seem kosher as you look around to verify this, get it resolved before actually doing it. Also follow the sequence when you actually do it. lilo before the boot disk or the boot disk is worthless.
Jeez, this was a lot longer than I anticipated.