Failed 1.4 upgrade (??)

Today i tried to update to mediawiki 1.3.5 to version 1.4.0

I am afraid that the included instructions are at all not clear (for 
someone whose native language is not English)

As far as I understand there is the Web installer, it doesn't say; but 
that would mean installing everything from the bottom up, risking to 
loose everything if a contradicting answer is given?

So I decided to take option 2: Command line upgrade.
Here my english failes: 'Additionally' does that mean you have to run 
the Web-installer AND the command line upgrade? Or is the command line 
script an additional option ('Additionally you *can* run...)?? Or can 
you just run the update script???
Then I spent a *long* time looking for the correct syntax of 
AdminSettings.php, until I noticed I had to copy AdminSettings.sample 
and edit it. It is not written in the UPGRADE, perhaps I am stupid and 
should have known!

So I decided t just run the command mode script, edited 
AdminSettings.php, and then I got the output:

============
> php update.php
Status: 404
Content-type: text/html
X-Powered-By: PHP/4.3.10

No input file specified.
============

And when I point my browser to the new install I get a blank screen...

Can somebody tell me what I have done wrong, and moreover: what I should 
have done? And then please no more guesses, just a cookbook recipe how 
to upgrade 1.3.5 to 1.4.0

Thanks!
Daniel