Clients with these cameras may wish to download the updates. The updates involve minor fixes as well as improving the brightness of the preview display. You can read more and download the firmware by following these links:
Version 1.0.3 for the Canon 5D
http://www.canon.co.jp/Imaging/eos5d/eos5d_firmware-e.html
Version 1.0.2 for the Canon 1D Mk2n
http://www.canon.co.jp/Imaging/eos1dm2n/eos1dmk2n_firmware-e.html
Read the instructions for using the updater very carefully, especialy about having a fresh battery or the mains adapter attached, you dont want to have the power on the camera shut down in the course of the update. If you wish I can perform the update whilst next on site.