Freebsd

Real World Web: Performance & Scalability

http://www.scribd.com/doc/2569319/Real-World-Web-Performance-Scalability 193 pages of realy good summaries on the topic

http://lists.freebsd.org/pipermail/freebsd-stable/2007-December/038735.html

http://lists.freebsd.org/pipermail/freebsd-stable/2007-December/038735.html freebsd and 8 cores horror stories