Setting up PHP Blog, Forum, Wiki, Gallery, etc...

I set up a Blog, Forum, Wiki, and Gallery on my forum, but I have a small problem, though not with those PHP applications. I have them all in separate directories blog/, forum/, wiki/, and gallery/ respectively all inside of www/, and I want the blog/ directory to be the target when you go to my domain name, but not set the document root to blog/, but to www/ so I can still have links from the blog to the others, like http://www.example.com/forum/. How would I configure this. My current site config look like this:

<VirtualHost *:80>
	ServerAdmin webmaster@example.com 

	DocumentRoot /var/www
	<Directory />
		Options FollowSymLinks
		AllowOverride None
	</Directory>
	<Directory /var/www/>
		Options Indexes FollowSymLinks MultiViews
		AllowOverride None
		Order allow,deny
		allow from all
	</Directory>

	ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
	<Directory "/usr/lib/cgi-bin">
		AllowOverride None
		Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
		Order allow,deny
		Allow from all
	</Directory>

	ErrorLog /var/log/apache2/error.log

	# Possible values include: debug, info, notice, warn, error, crit,
	# alert, emerg.
	LogLevel warn

	CustomLog /var/log/apache2/access.log combined

    Alias /doc/ "/usr/share/doc/"
    <Directory "/usr/share/doc/">
        Options Indexes MultiViews FollowSymLinks
        AllowOverride None
        Order deny,allow
        Deny from all
        Allow from 127.0.0.0/255.0.0.0 ::1/128
    </Directory>

</VirtualHost>

Code (markup):

Is there away to configure it here, or in a .htaccess file?

Thanks,
thelethargarian