replace nt4 pdc with w2k pdc

I’m trying to upgrade a computer and wanted to make move to w2k at same time. I am unable to setup the w2k machine as a backup domain controller. Is this possible? From what I’ve read, it now sounds my easiest approach would be to upgrade my existing nt4 pdc to w2k and then make my new server a backup. Then when I remove the old server I should promote the w2k machine to pdc. Only other alternative I’ve found is third party software and for one machine, and a small domain, that doesn’t seem practical.