There are plenty, depending on your method. In-place upgrade is usually not recommended unless you are certain that your 2000 server is squeaky clean without any inherent problems. An in-place upgrade is likely to just transport those problems and amplify them in the “new” server. If you want to use the Microsoft docs, then prepare for long nights and weekends, and a lot of down time.
I recommend using a toolkit available from http://www.sbsmigration.com which has a method to enable you to leave your production server running as long as possible, work offline with your upgrade as much as possible and preserve nearly all of your settings on the server AND the wokstations.
Declaration of interest: http://www.sbsmigration.com is run by fellow MVP Jeff Middleton. Although I have no direct financial gain to be made by recommending his method, I have a will to help him succeed.