WordPress MU

Hi,
I have problem with security, also i am confused. There is ability to change the blogs.dir and wp-content folder names for security reason as no one could enter there. But at the same time we use robots.txt which block or allows to access bots to this directory as the users also can easily determine our hidden folder names. My robots.txt for all sites:

User-agent: *
Disallow:
Disallow: /wp-admin
Disallow: /wp-includes
Disallow: /wp-login.php
Disallow: /foldername/plugins
Disallow: /foldername/cache
Disallow: /foldername/themes
Disallow: /trackback
Disallow: /comments
Disallow: */trackback
Disallow: */comments
Disallow: /*?*
Disallow: /*?
Allow: /foldename/blogsdirname/1/files/*

Sitemap: http://vsayt.com/sitemap.xml

Foldername = wp-content
blogsdirname = blogs.dir

What is our gain from these? Do we need to change folder names or just remove the folder names from robots.txt?

I figure that's just to keep the nice bots from indexing needless stuff about Wordpress. Any malicious script will determine that it's a wordpress installation within an instant and everybody knows the structure of wordpress, so no surprises there.

The best way to stay secure it to keep updating and be weary of plugins from unknown sources and audit what plugins do to your installation.

hmm, good recommendation, i will keep robots.txt . Seems it doesn`t matter to change wp-content/blogs.dir for security reason, that is for only make some modification for own site.

Thanks :)