Shoutbox

Codecs, like DivX, XviD always come in useful when you need to view stuff.
Also, for that matter, you could just install FFD Show, which renders videos and acts like a sort of universal codec for many MPEG-4 files, an ever more popular format for various video files and soon becoming a must have for every computer.
Even though its a PC that's mainly office based, its always a good idea to have your computer able to open a wide range of popular files...you never know what events may crop up when you want to view a file quick (e-mail from friends being the highest reason for this).

FFD Show