I was upgrading a SMS 2003 SP3 site server to SCCM SP1 earlier and notice that the SMS_SQL_Monitor service was not removed.
This is a know issue when upgrading from SMS 2003 SP2/SP3 to SCCM SP1 (I believe it only occurs in this one instance)
The fix is to manually remove the SMS_SQL_Monitor component after the upgrade.
You can do this two ways.
Reg Delete HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SMS\COMPONENTS\SMS_SITE_COMPONENT_MANAGER\Component Servers\SiteServerName\Components\SMS_SQL_MONITOR
Reg Delete HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SMS\Tracing\SMS_SQL_MONITOR
As always please backup your registry before making changes.