Here's a good guide on slipstreaming SP1 into Windows Server 2003, making a new CD that will directly install Windows Server 2003 SP1 (which is somewhat different than just installing Windows Server 2003 and applying SP1 afterwards).
A few tips I would add:
- Update the Support Tools on the CD by getting the Windows Server 2003 SP1 Support Tools.
- Update the Deployment Tools on the CD by getting the Windows Server 2003 SP1 Deployment Tools.
- To make a bootable CD, use IsoBuster in conjunction with Nero (which probably already came with your burner) by following these instructions. The instructions are for Windows XP SP2, but the bootable CD instructions work for Windows Server 2003 as well.