Well, for a mixed network you have three general choices.
Leave it up as PDC, but on its own segment and thus on it's own LAN stub and make a WAN bridge to it.
Migrate domain control to Novell.
Dump all IDS to paper, back up your DBMSs, build a new win2k domain server for domain control from your paper, destroy paper, and unplug your server overnight while you rebuild from a reinstall as file server and then backup recovery and possibly a reupdate. (Essentially your move, expedited).
Four would be more interesting, convert domain control (starting with LAN border entries) to OpenBSD-- which it excells at. OpenBSD, NetBSD, Linux, and Unix can all handle security function as multiple apps with individualized security by app. Thus, break part, you do not break all-- each brick can be secured individually and the gates can jail intruders in something that looks like a core plus data set but has false data (honeypotting is one extended variance of this).
To stage this box out, you could backup domain control to a backup server, separate DBMS to a DBMS server and take the box down if you can recover overnight. It while the box is down the data can be transfered on a faster box this might be possible to do in a short time (think of server's backedup HD's as source for data rather than server itself, move data to faster box inside HDs if can build file system in new box that mirrors old by either moving one half of the mirror temporarily to faster box for data recovery and transfer and leave second box live with minimal interruption to stick in new blank and let the array remirror itself).
Or wait until maint can get there and back up religiously so you have failover if the older box dies catastrophicly. Just a few ideas.
Since you have a need to have both up, you need to create on a second box while first is live, then stage up second box and take first down. Further, I would separate security control from any DBMS as far as physcial box if the money to do so is there or can be made available-- much more survivablility that way.
