A brain has actually been clocked I believe, I think it's around 1MHz or something like that, but it operates much more efficently than a CPU.
We actually had a discussion about a new technology, parralelism I believe it's called, which is currently in the experimental process, which will allow a CPU to perform tasks in the same fashion as a brain.
And a brain can store an endless amount of data, however it's not accessed in the same fashion as a hard drive, it's suppressed so to speak to it's more difficult to remember, but it's there.