A. Microsoft has a command-line tool called DuReg, which you can download at http://www.microsoft.com/windows2000/techinfo/reskit/tools/existing/dureg-o.asp. You can use DuReg to displays the total size of the registry or just the size of a particular part. Execute the downloaded file to install the application to the %SystemDrive%\Program Files\Resource Kit folder.

To retrieve the size of the entire registry, use the command with the /a switch, as the following example shows:

C:\Program Files\Resource Kit>dureg /a

Which will display the following output:

Size of HKEY_CLASSES_ROOT : 10259940
Size of HKEY_USERS : 2269159
Size of HKEY_LOCAL_MACHINE : 22187727
Total Registry data size: 34716826

To return the size of only a particular portion of the registry, use the command with the switch that specifies the portion of the registry (/cr for HKEY_CLASSES_ROOT, /cu for HKEY_CURRENT_USER, /u for HKEY_USERS, and /lm for HKEY_LOCAL_MACHINE) followed by the subfolder. For example, to determine the size of HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion, you use this command:

C:\Program Files\Resource Kit>dureg /lm  
  "SOFTWARE\Microsoft\Windows\CurrentVersion"
which will display the following output:
Size of HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion: 1923887