URL Rewrite for SSL redirection not working on remote

I'm trying to use URL Rewrite to push all traffic from http to https on my site.

I have read http://forums.iis.net/t/1153050.aspx?URL+Rewrite+for+SSL+redirection and my code is the same.

If I access my website from the W28k server, it runs as expected and the URL rewriting does it's job. 

If I try to access my site from any PC, I see  "500 - Internal server error"

I tried restarting IIS 7 after the change.

I assume that in IIS, I should be binding https to the IIS site (via a unique IP), and also the http: (via the 'normal' IP) to the same IIS site? 

Any idea what could be going wrong?