Wordpress Port Question

[Darryl Hoar]

Greetings,
I have a question regarding Wordpress and Wordpress-mu ports.   I want to
install wordpress 
on my personal webserver (apache2, mysql, etc).   I have several virtual
hosts all with 
legitimate individual domain names.  IE, www.mydomain.com,
www.anotherdomain.com, 
www.yetanotherdomain.com.   Do I need to install Wordpress or Wordpress-mu
on my server ?

The server has a clean install of Freebsd7 on it.

I googled for my answer, but the comparisons between the two did not make it
clear.

Thanks for any guidance,

-Darryl