We inherited a poorly configured Small Business Server 2003 that had under 1GB free space on it's operating system disk. As this box was obviously the domain controller we needed to find a quick solution to freeing up some space. Having already exhausted all other avenues for freeing up space we had decided that we didn't have a huge requirement at this point for the SBS monitoring. I found an excellent article which allowed me to fully remove the monitoring services which are installed by default as part of SBS. This allowed the removal of a SQL database (MSSQL) which was taking up almost 2GB alone.
The article describes how to reinstall the monitoring services.