Courtesy of Colin Jackson, a link to a hilarious xkcd comic: Kilobyte. Colin says:
WHAT EXACTLY IS A KILOBYTE? (OR A MEGABYTE, OR A GIGABYTE)
There is a lot of confusion about this out there – some of it deliberate – as I said on the radio last week, but the usual definition is 2^10 bytes, which is 1,024 bytes. Here’s a cartoonist’s take on the whole thing – it’s funny.