Advice on iframe vs template

I have a site that is on WP 3.0.4 and ATA 3.6 and I have a page set up with some iFrame code to display a google calendar within the framework of the site design. It is working, but when I go into the page via the WP admin, I cannot see the code in either the visual or HTML tab that loads the iFrame. Similarly, if I update the page, the iFrame functionality disappears off the live site.

I need to alter the code for something on the Google side. So I'm wondering if there is a better way to skin this cat.

My goal is to display the page as you see it now at: http://polkcitylibrary.com/calendar with the banner, nav and new scroll plugin at the top. No sidebars.

I'd love some opinions and experience to know if iFrame on a regular page is the right way to go with this, and what to do about the disappearing code or if I'd be better off making a new template and putting something in the Loop section to display the calendar. If template is better, please walk me through the process, I haven't done it in a long time and didn't easily find a step by step of the process in a quick forum search.

Thank you for all advice and input!
-Kimberly