Registry

HKEY_CURRENT_USER - This contains configuration information of a user who is currently logged onto the system. This stores all the user profile data. This actually an alias for a key in the HKEY_USERS sub tree.
HKEY_USERS - This contains all the user profiles on the computer.
HKEY_LOCAL_MACHINE - This contains configuration information particular to the computer, irrespective of which user is logged on.
HKEY_CLASSES_ROOT - This contains data that associates files types with programs and configuration data for COM objects.
HKEY_CURRENT_CONFIG - This contains information about the hardware profile used by the local computer at system startup.

Each key has a large number of subkeys and may actually have a value as well.

Registry Datatypes

REG_SZ	A fixed-length text string (True or False) values and other short text values usually have this data type
REG_EXPAND_SZ	A variable-length text string that can include variables that are resolved when an application or service uses the data
REG_DWORD	Data represented by a number that is 4 bytes (32 bits) long
REG_MULTI_SZ	Multiple text strings formatted as an array of null-terminated strings, and terminated by two null characters.

Microsoft.Win32.Registry

This provides base registry keys as shared public (read-only) methods
These can be used to access the subkeys for the corresponding keys

Microsoft.Win32.Registry oRegistry;

CurrentUser - HKEY_CURRENT_USER
Users - HKEY_USERS
LocalMachine - HKEY_LOCAL_MACHINE
ClassesRoot - HKEY_CLASSES_ROOT
CurrentConfig - CURRENT_CONFIG

Microsoft.Win32.RegistryKey

Microsoft.Win32.RegistryKey oRegistryKey;

Public Properties

Name	Retrieves the name of the key
SubKeyCount	Retrieves the total number of subkeys at the base level for the current key
ValueCount	Retrieves the count of values in the key

Public Methods

Close	Closes the key and flushes it to disk if the contents have been modified
CreateSubKey	Creates a new subkey or opens an existing subkey
DeleteSubKey	Deletes the specified subkey
DeleteSubKeyTree	Deletes the subkey and any child subkeys recursively
DeleteValue	Deletes the specified value from the key
Flush	Writes all the sttributes of the specified open registry key into the registry
GetSubKeyNames	Gets an array of strings that contain all the value names associated with this subkey
GetValue	Gets the specified value from the key
GetValueNames	Gets an array of strings that contain all the value names associated with this key
OpenSubKey	Gets a specified subkey, with the write access as specified.
SetValue	Sets the specified value

Creating a SubKey

Microsoft.Win32.RegistryKey oRegistryKey; 

oRegistryKey = Microsoft.Win32.Registry.LocalMachine.OpenSubKey("Software", true); 
oRegistryKey.CreateSubKey("MySubKey"); 
oRegistryKey.Close();

Deleting a SubKey

Microsoft.Win32.RegistryKey oRegistryKey; 

oRegistryKey = Microsoft.Win32.Registry.LocalMachine.OpenSubKey("Software", true) 
oRegistryKey.DeleteSubKey("MySubKey"); 
oRegistryKey.Close();

Reading and Writing

Microsoft.Win32.RegistryKey oRegistryKey; 
decimal dcDecimal; 

oRegistryKey = Microsoft.Win32.Registry.LocalMachine.OpenSubKey("Software\MySubKey", true); 
oRegistryKey.SetValue("MySubKey", "MyValue"); 
dcDecimal = objRegistryKey.GetValue("Version", 1.1);

Microsoft.Win32.RegistryKey oRegistryKey; 
string s64Or32 = ""; 

oRegistryKey = Microsoft.Win32.Registry.LocalMachine.OpenSubKey("Software\MySubKey", true); 
s64Or32 = oRegistryKey.GetValue("Bitness","N/A");