"... Covalent ERS is built upon a sturdy foundation of open-source software including Apache, Tomcat, Java, Perl and PHP. I've been using these packages for years. They are all free. So why would anyone choose to pay ,495 to use them with ERS?"
Covalent Enterprise Ready Server (ERS) 2.1 is a complete, integrated package of Web and application server software combined with an advanced Web-based management interface. For this review, I tested the single server edition (SSE) version of ERS on Windows 2000. However, it also runs on Solaris, Linux and HP-UX.