>Disk Cleanup does not empty c:\Windows\Temp. Does this mean the only way to clear that one is to do it manually, which means it is ok to do that?

One might assume so, but then I'd run across an occasional user that actually stored files in either the temporary folder. That doesn't surprise me one bit -- especially after seeing an occasional user that stored things in Recycle Bin folder. A bit more frequently I'd come across users who were in the habit of taking read E-mails and moving them to Trash -- and *expecting* the data never to be flushed.