..from what I recall installing ActivePerl asks/queries for association info upon install.

The defaults (and what I used) associated .pl files to be able to be run on the server like .exe files, .cgi files were associated with the perl interpreter for IIS mapping and I added .plx for the IIS 'plug-in' interpretation of perl scripts.

..thus the actual scripts called via the browser all needed to be either .cgi or .plx (both perl scripts) yet include scripts can remain .pl files.

-john