Setting default share permissions

If you use shared folders often, you probably know that Windows XP defaults share permissions to "Everyone" (with full access). If you don't know that - shame on you!
I don't know exactly where this default is stored, but if you want to change it, you can do with with the Tweak UI PowerToy.
In the tree on the left, select "Access Control". Then choose the "Default share permissions" in the combobox and click "Change".
Enjoy :-)