This article gives you the best and short view about new features available with the Server 2003 family when compared with the prior Server 2000.
List Of New Features:
1. Improved forest/Domain functional level mode like domain, forest and interim forest modes.
2. ADMT V2(active directory migration tool) with inter forest password migration and scripting support.
3. Domain and Domain Controller renaming.
4. Cross forest transitive kerberos trust.
5. Enhanced smart card authentication.
6. Software restriction policies(trusted binaries allowed based on path,hash and digital signature).
7. IP V6 Support.
8. Flexible wireless authentication.
9. DNS – Stub zones and conditional forwarding.
10. IPSec (features like IPSec NAT traversal, IPSec support in netsh, IPSec RSOP, IPSecMON in MMC).
11. Enhanced NLB (NLBMGR and ISA Server load balancing).
12. Storage services – Volume shadow copy support.
13. IIS 6.0 (features like kernel mode http and IGMP V3).