Hello,
If you use Windows 2008 servers you should use WBEM instead of SNMP. SNMP can be used but HP prefers WBEM. SNMP is configured in services SNMP in Windows. You need to give either all servers (IP) access or a set ofservers ( IP) adresses. Then you would set a trap destination (the SIM server). If you use the WBEM agent you can use SIM to set a subscription. Go to Options > Events > Subscribe tp WBEM events to let the agent know where to send it's events to. You can also use SIM to set your SNMP setting. Go to Configure > Configure and Repair Agents and fill the Configure SNMP bit.
If you need more hits regarding either let me know.