Good places to start:
Windows Server 2003 Technical Articles
2003 Server How-Tos

RRAS / VPN:
Securing Remote Access
Virtual Private Networking with Windows Server 2003: An Example Deployment
Step-by-Step Guide for Setting Up VPN-based Remote Access in a Test Lab
Remote access policies examples
The Cable Guy - January 2003 (PPTP)

Good detail on important concepts:
How DNS works
How TCP/IP works
What Are Domain and Forest Trusts?
How Domain and Forest Trusts Work
MS W2K3 chat archive

Reading up on NLB:
NLB Troubleshooting Overview for Windows Server 2003
NLB FAQ