Btw, the script is wise enough to work with .html extensions or not... so if you upgraded from an old version and Google already indexed your files, it will still point to that page.

Let's see:
http://www.teckwizards.com/forumdisplay/f-8.html
http://www.teckwizards.com/showthread/t-577.html
and:
http://www.teckwizards.com/forumdisplay/f-8
http://www.teckwizards.com/showthread/t-577
Same results.

Go ahead and upgrade your script.