Here are some articles from Microsoft about issues that may arise once you install Windows Server Service Pack 2 onto your system :
http://support.microsoft.com/kb/936594/ You may experience network-related problems after you install Windows Server 2003 SP2 or the Scalable Networking Pack.
http://support.microsoft.com/kb/939421 Best practices and known issues when you install Windows Server 2003 Service Pack 2 on a Windows Small Business Server 2003-based computer.