Upgrading secondary domain controller (2003 to 2008)

Hi everyone,

Recently I've upgraded our primary domain controller (direct upgrade) from server 2003 to 2008 without any issues. The active directory and all the replications appears to be working without any problems. With that being said, we still have another server 2003 domain controller (secondary) , which needs to be upgraded. My question is, is it the same process as upgrading the primary domain controller or is this little different?

I did a forestprep and domainprep on the primary controller, but is this required for the secondary domain controller as well?

Any feedback is appreciated, thank you!