Promoting Windows 2000 domain to Windows 2003

IF you are install another server with 2003 os, then you need to run adpred and domainprep from the 2003 disk on the 2000 server first.  Then install AD on the 2003 server and go.

Just to add to the above answer, here is a EE thread which i consider to be the most comprehensive upgrade guide

https://www.experts-exchange.com/questions/21410436/2000-to-2003-upgrade.html

What are weekends for, eh?

Before I defend why my answer is no more dangerous than yours, I would like to say that you answer is also correct.  If a windows domain is not taken care of properly, (IE upgrades, patched, hotfixes, the usual) most often they suffer the wrath when they try to upgrade.  Major issues will surface when running adprep and domainprep.  Little issues inside of active directory (unlinked containers and what not) will not be so apparant.  NTDSUtils and ADSIedit can be used to correct those issues.  I have also upgraded several hetrogenous domains with 10+ windows/unix servers in credit unions, law firms, banks, and local government agencies.  It is true that the environment needs to be pristine, however those are the steps required if a domain is maintained correctly.  

One line question with one answers leave alot of scope for interpretation - but don't make the answer any less right, just less comprehensive.

For example - I could also have been pedantic and said that cycle303's answer was not complete in that all you have managed is to introduce a 2003 server into a 2000 domain at 2000 DFL and FFL... whereas the poster asks "promote Windows 2000 domain to Windows 2003 domain " - again it depends on how you interpret this, but a literal interpretation could be decommisioning the orginal DC to then raise the FFL, or in place upgrade the OS of the old DC provided backups have been taken!

My link has pretty much all leew's concerns, but specified as an addition to the orginal answer rather than an alternative.

I'm sure if the poster has some concerns they can reply here...

I didn't say he was wrong... just that it was very dangerous -- because so few people have a perfectly managed Windows Server infrastructure.

I would wholeheartedly agree that precautions are taken place with any major change in AD, and this is one of the biggest you can make.

Backup the whole lot up 3 times! :D

Everything posted looks right.  Great job to all?

Thanks for the info, it was very useful!!