Calendar subscribing not working

Sorry for the double post - I posted this already at:
http://drupal.org/node/41319

But it is a critical part to help market my site.

Does anyone have this feature working with Windows visitors?

Go to here to see what the feature is (the ability for desktop Calendaring programs to subscribe to my list of events)
http://events.dowsett.ca/ical

HELP! :)
Many thanks,
Mark