File Permissions and User Management

So here's what I'm trying to do:

I have a department who wants to save all their files to the server. So they need the ability to be able to create folders, rename folders, and save files to the server. Once the files are saved to the server, they should become read only.

I've bee working with ACLs but they don't work...consistently. Basically, in some levels, it does this, and in others it allows the files to be deleted or renamed. And I've noticed that the behavior is spotty and have learned that ACLs are inherited from their parent, but must be created and will not be inherited if the file is simply moved. 99% of the time, the user will be working on this file on their desktop and will then drag and drop the file into the correct folder.

I'm sort of banging my head against a wall here. The ACLs seemed to work if I limited their delete ability, but Delete is required to rename folders. Which would mean that whenever they wanted to create a subfolder, they could create it but not rename it...which is pointless.

Can anyone help? Is there a better way? Anything?

Thanks,

S.