Well, actually, it isn't a real "upgrade" of running NT to 2000, but a "fresh" installation of Windows 2000 Professional. I hope it should also work for other Windows 2000 products. I haven't tried its server-type installations yet, but I remember I haven't experienced any problem with NT, regarding it was Server or Workstation.
First of all, a backup of important data should be made! I do it by having another Windows-like partition on the disk, where I copy/move my texts, drawings etc. That partition is not going to be handled during the installation. After the backup is made, it's the right time to install Windows 2000.
You see, folks, whenever I (re)install a Windows NT product, I like to see it on a clean partition. It means, I remove i.e. delete the existing partition where NT "system" files were stored, in order to get free ('unused') space. Then I chose to make a new partition that will be formatted as NTFS type of file system. After that, I opt to install Win2000 onto the new partition.
The procedure of Windows 2000 Setup will remove LILO from the MBR, so a couple of next re-bootings during the installation won't show LILO prompt.
When the Win2000 installation is finished, you may re-install your favorite applications and restore your data from the backup. You should then check if everything goes fine with your new and old Windoze stuff :-)
So far - so good. Now you have to look after your Linux boot floppy diskette. If you can't find it, you are out of luck. Actually, I am not sure if all Linux systems might be now activated without boot diskette. Some Linux gurus suggest to boot Linux from the installation CD, but I don't know if it can help in case your system doesn't have bootable CD-ROM drive, i.e. a modern motherboard's BIOS. Any comment here?
Well, after you successfully boot your Linux, you should go to /etc/lilo.conf to check it once again. You should have there at least two options: Linux and NT. Case you don't see the option to boot your beloved Windoze, you have to add it. It was described in previous sections. Then you have to run /sbin/lilo in order to put LILO boot loader into the MBR.
That's all. Next time you boot your computer, you'll get your LILO prompt. Using <Tab> key you'll see your boot options.
From my experience - all work great! Although I removed previous WinNT installation in order to make new Win2000 installation and also lost (temporarily) LILO boot loader, at the end I got both of them, Win2000 and Linux, the same way as I did with WinNT and Linux!