how to monitor ESX 4.x VM CPU usage using SNMP?

I am trying to use SNMP to monitor  the VM performances (include CPU, Memory, Network usage). My interested  info are defined in avaialble in VMWARE-OBSOLETED-MIB as  iso.org.dod.internet.private.enterprises.vmware.vmwResources.vmwCPU.vmwCpuTable,   .iso.org.dod.internet.private.enterprises.vmware.vmwResources.vmwMemory.vmwMemTable,   .iso.org.dod.internet.private.enterprises.vmware.vmwResources.vmwNetTable.

For  ESX 3.5 host, I can get those data successfully, but for ESX4.0 host  (vmwProdName.0:-->VMware ESX, vmwProdVersion.0:-->4.0.0,  vmwProdBuild.0:-->208167), I failed get those data, (I can still get  the  .iso.org.dod.internet.private.enterprises.vmware.vmwVirtMachines.vmwVmTable  data, so the SNMP server is work correctly).

My question -- in ESX 4.0, how can I get the equivilent performance data via SNMP for cpu/mem/network usage?