SNMP Question - Traps vs Non Traps

I am trying to monitor certain information via SNMP.. Specifically:

Temperature

Fan Status

I have found a MIB for Compaq servers ( CPQHLTH.MIB Compaq Server Health information) that is able to pull this information.. However, I can only seem to add them as "traps". In the OpManager MIBBrowser I can actually get the temperature but I don't see how I can add that as something I monitor..

I guess what I'm confused about is how some SNMP things are listed in the "Add Monitor" section whereas all the "Traps" are not.. The only place I see them is in the "Alert" section..

Please advise.

Thanks