Using the dirsize.dll plugin from MVP Mark Dormer, you can add the Folder
Size column for folders in Detail View. This plugin calculates the folder
size and displays it in a column. Download Dirsize.dll plugin and place the
file in Windows\System32 folder. Now, register the DLL using regsvr32
command from Start, Run dialog.
regsvr32 %Systemroot%\System32\Dirsize.dll
Next, open a folder and set it to Detail view. From the View menu, click
Choose Details. Put a checkmark near Folder Size, and click OK. Use CTRL and
+ key (Numeric Keypad) combination to resize the column width, so that the
Folder Size column is displayed correctly.
To apply this setting for all the folders, click Tools, Folder Options. In
the View tab and click Apply to all folders. To remove the feature, simply
un-register the DLL [regsvr32 /u %Systemroot%\System32\Dirsize.dll]. Ignore
error messages if any.
You can download the module from here:
http://markd.mvps.org/home.asp