As I promised a few days back, here's a complete video of Comet McNaught passing through the LASCO camera on SOHO telescope.
You can really start to see the solar wind fan the tail out as it goes around the Sun, which is why images in the northern hemisphere, show a largely straight tail, yet ones in the southern hemisphere show a much more diffuse tail as the solar wind pushes the tail away from the Sun.
The reason it looks so over-exposed is because the LASCO camera is designed to look at the faint outer atmosphere of the Sun. Even the planet Mercury, shown in this footage to the lower left causes the pixels to bleed into each other creating horizontal lines. Comet McNaught is far too bright to be properly exposed.
You can find more information about SOHO on the SOHO website, or download the videos here.