||Scaling Dynamic Websites with Apache Modules|
I had a website running on a P4, 2,4 Ghz, 1GB ram with 200 lightweight apache and 30 mod_perl apache, serving 20.000 users with 10 GB data per day.
The lightweight apache worked as proxy and had only to serve static content (images , stylesheets ) while the mod_perl apache was running HTML::Mason and building each page out of the database. The max. load was about 1.5 (with full number of apache) and below 0.5 most of the time. A diagramm showing this over an 24 hour period can be seen at http://www.plusw.de/images/apache_fe_be.gif.