It shouldn't make a difference if it's in an I-frame or not. Personally I would skip the I-frame.
There is so much frontpage/microsoft only code on your site I'm not sure what is causing the active-x issue. It's one the vml objeects that's callng to run the mosrun.dll file from a users system.
This is also the issue with the mailto links. They are inside microsoft specific code. (they don't link at all in other browsers) The layout is probably set to position:aboslute while the center content is set to relative. The center content will center itself in the middle of the borwser window no matter the width, while the mailto items stay at the same pixel position. Drag the bottom right corner of your browser window smaller and larger and you will see this effect.
Also for you info, much of your layout and content is Internet Explorer specific. Standard compliant browsers display your site ignoring microsoft specific code. Download another browser to see how some of your visitors view the site. (you can run more that one browser with out any issues) Firefox web browser | Faster, more secure, & customizable Opera browser: Home page Apple - Safari - Download