Why do you want to delete contents of Windows\SoftwareDistribution\download?
Are you running seriously short of hard drive space in your Windows partition? If not, then I am inclined to suggest leaving that folder as-is.
Anyway, I Googled your thread title
. Perhaps some of those links will help answer your question.
I do not
know how reliable the information in those links is.
If you decide to "delete" the contents of your Windows\SoftwareDistribution\download folder, then I suggest you at least back up that folder by copying it to another partition/folder or to CD (to be on the safe side). EDIT:
If you are having trouble with Windows Update, then perhaps the following link will help instead of
deleting the contents of the Windows\SoftwareDistribution\download folder.