URL change with IIS6

I have 3 WP sites set up on a Windows 2003 server and I am using IIS. While doing the setup everything has been on the local network. I have not opened the server up to the internet yet. When we originally set these sites up we were using .com on the domain because the preferred .org domain was tied up on another site. I have since freed up .org and got an SSL cert (for .org) installed etc. I’ll make a long story short and say that any change on the URL settings in WP breaks the sites. The one site that I tried I got back by adding the URL’s to the wp_config file. I’ve been looking for information on this but I can’t find a good document that pertains to IIS. Any help would be appreciated.