> At present, the script looks for the name and tripcode in different fields, and I don't want to change that in the script.

For what reason?

> What's wrong with the current captcha system?

It's big, hard to read, and looks quite out of place.

> Clearly I was wrong.

Not really. I much prefer the current version.

Another suggestion: get rid of the "File 1:", "File 2:", etc. The "File" part is redundant.

By the way, the text touching a border issue that WAHa mentioned also appears in Opera. Take a look at the left edge: http://wakachan.org/junk/thorn-css.png. I'd also like to draw your attention to the location of the title at the bottom of the page.