I've got XP Home and I was using Firefox, H.
Some people are able to see these characters using IE & others can't, which makes me think a setting needs tweaking somewhere.
The site Hooligan is referring to is: click here
and the characters he's looking for are at the bottom of the 2nd page of the form. It is a randomly selected set of characters that show up as an image and he needs to see these characters to be able to enter them into an adjacent box.