domain upgrade to 2008 by adding new 2008 server

I want to upgrade a domain Windows 2000 with 2 DCs to windows 2008 and I also want to add a brand new server for the 2008 DC. I was able to find some tips but still I have some questions. After the phase when the schema is prepared for 2008, how problematic will this be? Will I need to have all member servers fully shutdown? Also can the schema be prepared in advance? How can I find out if I can minimize the maintenance window. Incase RRAs is in use as VPN server in the 2000 domain, is that going to contine to work under 2008 provided the 2 initial DCs will be left as thet are? Thanks

You can try to run a System State Backup of one of your DC's and then you can extend the domain and forest with your adprep. It should not impact your original DC, you can apply this too but depending on the number and connectivity of the DCs, replication may take a bit of time. You can try to do that at the end of the day.

Thanks for the reply. It is much appreciated.

You can also try to upgrade the schema without any issues in running systems. You just need to create a system backup before for the case that something goes wrong. It will not have any effect on the member server, even if you change functional levels, that only effects Domain Controllers and not member servers.