just wanted to offer a bit more help:
first you'll need to decide such things as:
1. are these publicly available domains?
2. do you have access to a single or multiple static IP's?
3. do you have FQDN's for all virtual hosts?
anyways here's what i have running on my mac os x box: i added these directives to the end of my /etc/httpd/httpd.conf file
NameVirtualHost (ip address of your host here)
<VirtualHost 192.168.0.1>
DocumentRoot "(indsert path to your content here)"
ServerName (insert name of your server here--a fully qualified domain name)
</VirtualHost>
<VirtualHost (ip address of your host here)>
DocumentRoot "(insert path to 2nd web content here)"
ServerName (insert name of your 2nd server here--a fqdn)
</VirtualHost>
there are also a few tutorials at
www.apache.org that you can read. alternatively you can read the apache docs that come with mac os x in /Library/Webserver/Documents/manual
ppmax