Depends on lots of things, Sean, including how tall and heavy you are, how much you run, how much other exercise you do, whether you have an active or sedentary job, whether you want to lose, gain or maintain weight, what sort of stuff you like to eat, whether you can train with a full belly, and that great unknown, biological variation.
There is, as Jeremy says, some brilliant general advice in the nutrition section. There are also several good books on sports nutrition - Liz Applegate's "Eat Smart, Play Hard" is very readable but the menus are far too American for me (bagels! blueberries! dried egg white powder! defatted soy flour!). Anita Bean's books are more relevant to an athlete on a British diet.
When it comes down to deciding what to eat, one size doesn't fit all and if you don't have a personal trainer dictating what can go on your plate you have to work it out yourself based on trial and error.
One tip from personal experience. No matter how much stilton cheese you eat before a run, it will not put glycogen in your muscles.
Cheers, V-rap.
Cheers, V-rap.