Is there any reason not to delete the contents of \downloaded installations and
\downloaded program files ?
I would not delete them unless you know what they are. Because the
next time you go to a web site that needs the items in the downloaded
program files folder, you will have to download and install them
again.
A good example of what is in there...if you are a user at the Pogo
games site, all the active X games you play at the site are in that
folder.