How to prevent users moving files from a folder that they can edit files in

@Driftpeasant's answer is a good one. The other thing associated with only granting access to a single file is that it can cause some serious application headaches. For example some apps will create temporary files in the same directory as the file (word) or will delete and recreate the file when saving (some mathematical applications, among others).

In the case of the delete and recreate this is very problematic as the newly created file will inherit the permissions from the folder, erasing whatever permissions changes were previously made. This is in line with @Zoredache's comment. I would suggest a folder or sub folder from that you want kept read only.

TO clarify, I need to stop users from creating or moving files INTO the C:\bin folder which are not executables.

I think what you want is a File Screening policy using the File System Resource Manager available on Windows Server 2008 and later. You can have a policy that only allows *.exe to exist in a certain directory.

From the linked document:

Create file screens to control the types of files that users can save and to send notifications when users attempt to save blocked files.

Define file screening templates that can be easily applied to new volumes or folders and that can be used across an organization.

Create file screening exceptions that extend the flexibility of the file screening rules.