If you are monitoring Windows XP machines that are not in a domain, it is necessary to have simple file sharing enabled. This will force all remote connections (including WMI queries) to be handled through the guest account.
To monitor such a system, you must either grant the guest account WMI and DCOM rights, as explained here, or, preferably, disable simple file sharing so that the remote access can be authenticated appropriately, either as a local administrator or another account that has been given permission to DCOM and WMI remotely.
To disable simple file sharing, follow these steps:
- Click Start, and then click My Computer.
- On the Tools menu, click Folder Options, and then click the View tab.
- In the Advanced Settings section, clear the Use simple file sharing (Recommended) check box.
- Click OK.