WordPress MU

Hi. I'm thinking about using Wordpress Mu on my site since I need about five separate wordpress blogs on my website. QUESTION: If a site visitor wants to comment on my blogs, do they need to create a separate username and password for each separate blog in order to comment?
Thanks!

No.

okay...? :-) So that means people login once on my site somewhere (where?) and then can comment on allll the blogs with that ONE username and password?
Thanks for any elaboration!
Kristin

If you set it so users have to be logged on to post comments then yes that is how I understand it works.

Users can login on the main page if you have a link for them. Heck, if they've done it a few times' they'll know the URL.

Once a user is logging in from the main page they are indeed logged in site-wide.

They will only be able to comment on blogs on the same domain.

They'll need to log on again (same login though) for any other domains hosted on the same install.

Thanks for answering this question :) How do i set it so that all blogs created on my wpmu install by default require login for commenting? I didn't find it in the options

ok, I so i found it. I found a way to edit a file. Any one has a more elegant way of doing it?
I edited wp-admin/upgrade-options.php (populate_options() function) to add
+ add_option('comment_registration', 1);

But this means i have a custom wp-mu file

Just keep track of it and whenever you upgrade, make sure you re-edit the file.