GridRM is an open and extensible resource monitoring system, based on the Global Grid Forum's Grid Monitoring Architecture (GMA). GridRM is not intended to interact with applications; rather it is designed to monitor the resources that an application may use. This paper focuses on the pluggable driver infrastructure used by GridRM to interact with heterogeneous data sources, such as local SNMP or Ganglia agents, and how it provides a homogeneous view of the underlying heterogeneous data. This paper discusses the local infrastructure and details early work on implementing and deploying a number of drivers.