Large image in post breaks layout please help

Hi I am using the Xenon theme on my site I have few large images in posts, and they break the posts, I tried adding some br tags but it did not work and they were stripped.

Please help me see the link here
http://newsite.colorprintingcentral.com/letterhead-and-envelopes.html

this is the theme link
http://www.fabthemes.com/xenon/

left column is supposed to be the same height as primary div

-Thanks