First, download the service pack from Microsoft's Web site by searching for "service pack" and selecting "SQL Server" as the product. You should be able to easily locate the service pack needed for your SQL Server product version, download it and store it on a file server if you want to prevent having to burn it to a CD.
Before you proceed with deployment, you should back up all user databases as well as the master, msdb, and model databases on each SQL Server instance. In addition, you'll need to inform personnel who depend on those systems about the downtime window since it can be quite large for service packs.
HOW TO PATCH SQL SERVER, PART 2
Step 1: Segregate your scan results
Step 2: Obtain service packs and prepare for deployment
Step 3: Deploy service packs
Step 4: Obtain hotfixes and prepare for deployment
Step 5: Deploy hotfixes
Step 6: Re-assess network
Step 7: Plan next assessment
Back: How to patch SQL Server, part 1
ABOUT THE AUTHOR:
Chip Andrews is the director of research and development for Special Ops Security Inc. and the founder of the SQLSecurity.com Web site, which focuses on Microsoft SQL Server security topics and issues. He is also the author of SQL Server Security.