How to list all folders greater than a specified size?

That is a great idea! Here's the rest of the code:

@echo off

setlocal

set srcDir=c:\
set outFile=%cd%\output.txt
set /a threshold=500000000

if exist "%outFile%" del "%outFile%"

pushd "%srcDir%"

for /f "tokens=1,2*" %%a in ('dir /s /-c ^| findstr /r " bytes ^| Directory "') do call :PROCESS "%%a" "%%c"

popd

if not exist "%outFile%" (echo No directories are over %threshold%)>>"%outFile%"

echo Results in %outFile%

goto :EOF

:PROCESS

if "%~1"=="Directory" set dirName=%~2&goto :EOF

call :GETBYTES %~2

if "%bytes%"=="" goto :EOF

if /i %bytes% GTR %threshold% (echo %dirName% has %~2 bytes)>>"%outFile%"

goto :EOF

:GETBYTES

set bytes=

if "%~3"=="free" goto :EOF
if "%~2"=="bytes" set bytes=%~1

goto :EOF

Try diruse.exe from the Support Tools, for example like this:
diruse /s /d /m /q:500 C:\
/l would create a logfile diruse.log in the folder you're in when you run the command.

Windows Server 2003 Service Pack 1 32-bit Support Tools
http://www.microsoft.com/downloads/details.aspx?FamilyId=6EC50B78-8BE1-4E81-B3BE-4E7AC4F0912D&displaylang=en

Windows Server 2003 Service Pack 2 32-bit Support Tools
http://www.microsoft.com/downloads/details.aspx?FamilyID=96a35011-fd83-419d-939b-9a772ea2df90&displaylang=en

If you wouldn't mind using a VBS version, here's one that outputs to Excel and sorts the folders by size (using Excel, so kind of cheating, but hey, it's easier!).

NOTE: You must have DirUse.exe in your %systemroot%\System32 folder.

'============
'================
strLogFileName = "Results.txt"
strResultsFile = Replace(WScript.ScriptFullName, WScript.ScriptName, "") & strLogFileName

strFolderToCheck = "C:\Temp"

Set objShell = CreateObject("WScript.Shell")
strCommand = "cmd /c diruse /s /m " & """" & strFolderToCheck & """" & " > """ & strResultsFile & """"
objShell.Run strCommand, 0, True

Set objFSO = CreateObject("Scripting.FileSystemObject")
Const intForReading = 1
Set objResults = objFSO.OpenTextFile(strResultsFile, intForReading, False)
While Not objResults.AtEndOfStream
      strLine = objResults.ReadLine
      'If InStr(strLine, "Size (mb)") = 0 Then
            If strLine <> "" Then
                  strNewLine = Trim(Left(strLine, 13)) & "|"
                  strNewLine = strNewLine & Trim(Mid(strLine, 14, 7)) & "|"
                  strNewLine = strNewLine & Trim(Mid(strLine, 21))
                  If strResults = "" Then
                        strResults = strNewLine
                  Else
                        strResults = strResults & VbCrLf & strNewLine
                  End If
            End If
      'End If
Wend
objResults.Close
Set objResults = Nothing
objFSO.DeleteFile strResultsFile, True

'MsgBox strResults

Set objExcelApp = CreateObject("Excel.Application")

Const xlAscending = 1
Const xlDescending = 2
Const xlCalculationManual = -4135
Const xlCalculationAutomatic = -4105
objExcelApp.Visible = True

objExcelApp.Workbooks.Add
objExcelApp.Calculation = xlCalculationManual
objExcelApp.ScreenUpdating = False

arrResultsRows = Split(strResults, VbCrLf)

ReDim arrResultsTable(UBound(arrResultsRows), UBound(Split(arrResultsRows(0), "|")))

For intRowNum = LBound(arrResultsRows) To UBound(arrResultsRows)
      For intColNum = LBound(Split(arrResultsRows(0), "|")) To UBound(Split(arrResultsRows(0), "|"))
            objExcelApp.ActiveSheet.Cells(intRowNum + 1, intColNum + 1).Value = Split(arrResultsRows(intRowNum), "|")(intColNum)
            'arrResultsTable(intRowNum, intColNum) = Split(arrResultsRows(intRowNum), "|")(intColNum)
      Next
Next

objExcelApp.ActiveSheet.Cells.Select
objExcelApp.Selection.Sort objExcelApp.ActiveSheet.Range("A2"), xlDescending, , , , , , 1, 1, False, 1
objExcelApp.ActiveSheet.Range("A1").Select

'objExcelApp.Calculation = xlCalculationAutomatic
objExcelApp.ScreenUpdating = True

MsgBox "Done"
'===============

Regards,

Rob.