I spent alot of time trying to get my apache config correct so I am sharing what works for me on apache-2.0 and php5 on a RHEL3.0 linux server. This is a file under conf.d called sample.org.conf or you can put it in the httpd.conf and be sure to restart apache:
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# sample *dns virtual host -elly 9/16/05
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<VirtualHost *:80>
ServerAdmin server@sample.org
# Temporary dns (wildcard)
ServerName mu.sample.org
ServerAlias *.mu.sample.org
Customlog /var/log/httpd/sample_access_log combined
Errorlog /var/log/httpd/samle_error_log
DocumentRoot /var/www/html/wpmu
<Directory /var/www/html/wpmu>
Options FollowSymLinks
AllowOverride All
</Directory>
</VirtualHost>
