Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

type
   PSHQueryRBInfo = ^TSHQueryRBInfo;
   TSHQueryRBInfo = packed record
     cbSize: DWORD;
     // Size of the structure, in bytes. 
    // This member must be filled in prior to calling the function. 
    i64Size: Int64;
     // Total size of all the objects in the specified Recycle Bin, in bytes. 
    i64NumItems: Int64;
     // Total number of items in the specified Recycle Bin. 
  end;

 const
   shell32 = 'shell32.dll';

 function SHQueryRecycleBin(szRootPath: PChar; SHQueryRBInfo: PSHQueryRBInfo): HResult;
   stdcall; external shell32 Name 'SHQueryRecycleBinA';

 function GetDllVersion(FileName: string): Integer;
 var
   InfoSize, Wnd: DWORD;
   VerBuf: Pointer;
   FI: PVSFixedFileInfo;
   VerSize: DWORD;
 begin
   Result   := 0;
   InfoSize := GetFileVersionInfoSize(PChar(FileName), Wnd);
   if InfoSize <> 0 then
   begin
     GetMem(VerBuf, InfoSize);
     try
       if GetFileVersionInfo(PChar(FileName), Wnd, InfoSize, VerBuf) then
         if VerQueryValue(VerBuf, '\', Pointer(FI), VerSize) then
           Result := FI.dwFileVersionMS;
     finally
       FreeMem(VerBuf);
     end;
   end;
 end;

 procedure TForm1.Button1Click(Sender: TObject);
 var
   DllVersion: integer;
   SHQueryRBInfo: TSHQueryRBInfo;
   r: HResult;
 begin
   DllVersion := GetDllVersion(PChar(shell32));
   if DllVersion >= $00040048 then
   begin
     FillChar(SHQueryRBInfo, SizeOf(TSHQueryRBInfo), #0);
     SHQueryRBInfo.cbSize := SizeOf(TSHQueryRBInfo);
     R := SHQueryRecycleBin(nil, @SHQueryRBInfo);
     if r = s_OK then
     begin
       label1.Caption := Format('Size:%d Items:%d',
         [SHQueryRBInfo.i64Size, SHQueryRBInfo.i64NumItems]);
     end
     else
       label1.Caption := Format('Err:%x', [r]);
   end;
 end;

 { 

The SHQueryRecycleBin API used in this method is 
only available on systems with the latest shell32.dll installed with IE4 / 
Active Desktop. 

}