It doesn't matter if you have <VirtualHost *>, just as long as you specify the ServerName.
Remember that namebased virtual hosting is based off the client browser. It pulls the url it's after from the headers I believe. Therefore, it's not always accurate ( users of older browsers ), but will be fine for 99% of users that hit your site(s).
The above configuration works fine for the 75+ sites i have setup on my linux box, so it should work fine for you. To test domains that don't exist by your account, alter your hosts file in:
windows > system32 > drivers > etc > hosts
then, use "domainname.com" in your browser to test it.
Hope that helps