The security attribute that would prevent the user from seeing the contents of the folders would be the "List Folder Contents"; you would want to remove all other permissions and set the "list" permission to "Deny." However, you can't do this at the folder level itself. In other words, they would still be able to see the folder but they would not be able to open it or view the contents of the folder. I don't know of any way to actually hide the folder itself.
If the users are grouped in such a way that you can identify different groups of users who all need the same subset of folders, I would say that a better alternative would be to move the folders into separate shares by group and then map the drive letter depending upon which group the user belongs to. This can be accomplished by using the "ifmember.exe" resource kit utility; this utility allows you to check group membership from a login script and then set the script to perform drive mapping(s) only if the user is a member of the particular group.
If this solution will work for you, and you need help with the scripting, I can email you directly an example of a script I use to do this sort of thing.
Hope this helps!