Here is a way I had to do it when my Win95 crashed after a motherboard bios update was installed. I was dual booting win2000 with win95. This way is somewhat not the best way but it does work providing you have it installed on a FAT/FAT32 partition. Boot off a windows start up disk and ensure that that the floppy has the deltree command on it. Start by removing all attributes from the WINNT directory with the "attrib *.* -h-r-s-a /s" command. Then delete the directory using the deltree command. Then do the same process to the user settings directory. Then delete the pagefile.sys file. Then fdisk/mbr the active partition. Then sys the same partition. When you boot up again you should get to a c:> prompt and from there, install a windows based OS. In my case I reinstalled Win95 on a freshly formatted partition and I will be re-installing Win2000 onto the other partition once I have a little time.
 
[This message has been edited by Tim Bazzinett (edited 24 December 1999).]

You could do it that long complicated way or simply
1. boot into 9x and format partition with win2k
2. Reboot with floppy and format c: /mbr then do a sys c:
3. Delete the ntloader and any other files associated with it off your active boot partition
 
or if you plan on installing a duel boot again don't bother with steps 2 & 3
 
[This message has been edited by Seldzar (edited 24 December 1999).]