Sizing Tools for MOM and SMS
Microsoft released some great sizing tools for MOM and SMS, You can use them to plan the Hardware Capacity for each of the MOM and SMS component.
MOM 2005 Sizer
The MOM 2005 Sizer provides recommendations for MOM server configurations based on modeled workloads.
SMS 2003 Capacity Planner
A planning tool that helps consultants, SMS administrators, and IT professionals perform scenario analysis on their existing and proposed SMS 2003 hierarchy
System Center Capacity Planner
Microsoft System Center Capacity Planner 2006 helps size and plan deployments of Microsoft Exchange Server 2003 and Microsoft Operations Manager (MOM) 2005. It provides you with the tools and guidance to deploy efficiently, while planning for the future by allowing for "what-if" analyses.