encyclo - 11:51 pm on Mar 16, 2009 (gmt 0)

I assume you're using Apache? If so, then you need to set up the appropriate (usually name-based) VirtualHosts in httpd.conf, defining the appropriate document root for each:

[httpd.apache.org...]

I'm not a fan of placing subdomains or add-on domains as subdirectories of a primary host, as it can complicate management of any redirects and such as any rules for the primary domain risk cascading down to the subdomains. You would be better preparing separate document roots for each domain, maybe with common content defined via an Alias [httpd.apache.org]. On a Linux/Unix server, you can use a user directory for each domain instead.