You will also need a 2008 licensing server as well. Normally the terminal server and licensing server are different machines. Thats one difference and one reason I havent upgraded yet, along with you will need to buy 2008 cals. I believe you can buy upgrade cals.
Other then that the underlying differences from 2000 to 2k8 are big
http://technet.microsoft.com/en-us/library/cc733093.aspx