For Windows, what other frameworks or programming languages I could use that are similar to WMI's monitoring and system management functionalities?
Most comparable to WMI's performance monitoring features is SNMP (Simple Network Management Protocol). It's standard on all Unixy and network devices, but a little less frequently used on Windows. Check out the Net-SNMP site for loads of info. Also, I'd recommend using the free SNMP-Informant Standard Edition program to beef up Windows' ability to report via SNMP.
Other features of WMI are covered in other protocols like Perfmon for performance statistics, and ADSI or LDAP for authentication & authorization.