Prevent students running exe files from anywhere other than C:\Program Files

Dear Experts,

I've recently inherited the support of a large secondary school, and it looks as though students have the ability to run executable files from various locations.

I've locked down their networked drives using file screening, but is there a way I can prevent users from running exes that are downloaded from the net and presumably run from temp internet files?

Ideally I like to restrict the running of exes to the C:\Program Files folder only.

Any advice gratefully received.