ACL= Access Control List

I haven't played much with the lower versions of W7 (assuming yours is?) but in the case of XP Home Edition, you have 'Simple File Sharing', only with the 'Professional' version you have proper access control (and even that wasn't enabled in a workgroup environment)

If this trait follows in 7 you might not have it, either way if you go into the folder properties and click the 'security' tab, it should list the respective users, groups and there permissions...

Martin