Block download by file extension

I am trying to find a simple way to block the download or online execution of three file types: .wmf, .emf, & .apm.
Any ideas.... I have searched various help sites but this really eludes me. Seems like it should be simple. Any help is very much appreciated.

 

Of possible help
http://www.google.com/search?source...GGLD:2004-31,GGLD:en&q=block+download+of+.emf
Some antivirus programs also will do this.

 

On Help for blocking of files by ext.

Many Thanks! Seems to be working..... Regards. M

 

Martin E--Thanks for posting back. Always good to hear that a suggestion was of help.