Below is a copy-paste class with a lot of VB.Net functions which allow you to query your computer information using WMI queries. Hope it helps.
Computer Information (OS, OS Version, Manufacturer, Computer Name, Windows Directory, Total RAM (in MB), Free RAM (in MB), Free Ram Raw, Total Ram Raw)
List of all shares (Share Name, Share Path)
List of all local drives (Device ID, Used GB, Total GB, Provider Name, Description)
List of local services (Name, Description)
List of all Network adapters (NIC Description, MAC Address, DHCP Enabled or not)
List of all Startup programs (Full path)
List of local printers (Device ID)
Registry Maximum size and current size
Intial Page Size and Maximum Page file size.
Video card Chip Type and Video Ram size
Checks if a given process is running or not.
PS: Some people have been asking about the ImpersonateValidUser helper function that is missing in the WMI.vb class. Here is the function if you need it.