file permissions: can this be done?

Hi

To limit the effects of a potential virus, I want to do the following
for the Limited User account:

1) all current files and folders in My Documents can only be read.
Contents of files may not be modified. No items may be deleted

2) however..... new files/folders may be created in My Documents. These
user should have Full Control over these files.

Then once a month or so, I run a batch script which changes the
permissions of all newly created files (items under 2) to become more
restrictive (1)

I thought this would be pretty simple, but somehow I cannot get this to
work. It is driving me crazy.


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bobob21