Server 2003 in a 2000 Forest

Does anybody know, or has anybody brought up a Child domain running Server 2003 as it’s Domain Controllers in a Forest that is all on Windows 2000 servers? What are the implications of such an undertaking, and should it be done, or is it something that should be avoided? Are there any schema modifications that have to take place to make this happen, or are there any other Forest wide changes that have to be made to make this work properly? Please explain.