There is several options to solve that.

option 1: Try to create module folder somewhere else, say on desktop, then create shortcut to this folder from C:\Program Files (x86)\Odoo 8.0-20150805\server\openerp\addons (with the same name as module folder name) and check if such approach will work... (I never tried but it may work, I do not use windows actually)

option 2: You can always reset security settings for  C:\Program Files (x86)\Odoo 8.0-20150805\server\openerp\addons such a way, that it'll allow you further edit everything inside it (of course you'll need administrative access for that).

option 3: Edit configuration file of odoo (openerp.conf or something like that) and add additional addons directory path to another directory, where you can add your modules, or even you can edit windows service for odoo(from services) and add additional addons directory path through --addons-path command line option.