Unable to make changes to PHP53_viaFastCGI Handler

Hi there, 

I need to add the PUT verb to the PHP53_viaFastCGI Handler Mapping.  Anytime I try to make any kind of change to the Handler, I receive the following message "Edit Module Mapping:  The specified executable for the handler must be a .dll or .exe file.  If the path to the script processor (only in the case of a .exe file) has spaces, use double quotation marks to specify the executable."

Any suggestions?  

Note: I have very little experience with IIS.