Arlindo Alves the Belgian IT Pro Evangelist wrote a blogpost series about 10 Reasons you want to look at Windows Server 2008. It's a great introduction into the new features and services this new Operating system will deliver.
Part 1: Server Management Improvements
Part 2: Windows PowerShell
Part 3: Internet Information Services 7.0
Part 4: Server Hardening
Part 5: Server Core
Part 6: Network Access Protection
Part 7: Windows Failover Cluster
Part 8: Branch Office Deployments
Part 9: Windows Server Virtualization
Part 10: Terminal Services
Enjoy the reading.