Missing WMI Classes in Exchange 2007

Hi

Some of the WMI Classes present in Exchange 2003 are Missing in Exchange 2007 such as for eg. Win32_PerfRawData_MSExchangeMTA_MSExchangeMTAConnections,Win32_PerfRawData_MSExchangeMTA_MSExchangeMTA,Win32_PerfRawData_SMTPSVC_SMTPServer etc..
is there any command or utility to reregister the above WMI Classes in Exchange 2007 ???

Plz help

Thanks & Rgds
Roshini