I want to prevent users from going to say example.com and only go to www.example.com, we are using IIS 6. So say they go to example.com it could tack on the www.example.com, etc.
Is this a setting somewhere or will I have to code it to check for the subdomain when they land and redirect accordingly?
EDIT: I know the best way is to move away from the www prefix but for whatever reason if the user launches a course (this is an LMS) without the www in the URL the tracking does not work for the .asmx file, that is why I am trying to force the 'www' because if some people don't have it then they wonder why the tracking does not work.
As both records already point to the correct server...
...you could simply set up a new website in IIS (server version needed) and have it respond only to example.com (the host header setting) and have it redirect to the wanted url (check redirect to url in Home Directory tab and enter www.example.com). The original site should then handle it (you could set it's host header to answer to www.example.com to be more specific).
If you can't do that on the web server, your publishing firewall should be able to, or you might consider replacing it. Your DNS provider might also provide (pun not intended) a redirect service (doing basically the same thing as above for you I guess).