localhost.localdomain instead localhost in a Windows VPS

Hello All: I am very new on WordPress and trying to do things right from the beginning I am driving crazy setting up multi sites, because I don’t know how to use localhost.localdomain instead localhost, and for that reason I haven’t been able to setup a multi site sub-domain network, it only give me the option of a sub-directory network. I am setting up WordPress using Web Platform Installer on my Windows Virtual Private Server. Please advise how can I use localhost.localdomain instead localhost…

The below link has exactly the message I get from WordPress: http://codex.wordpress.org/images/7/7c/tools-network.png

Any help will be highly appreciated…