Originally Posted by till
Howtoforge uses a main Server with DualCore AMD processor and a second server as replicated backup server in case the first server fails. We also use two additional servers to serve static content like the images in the howtos.
The key point in running a site with many concurrent users is that you need much ram for caching SQL queries and that you use a PHP cache. The first bottleneck you will reach is mostly the harddisk transfer rate and not the power of the processor.
Those information are very useful to build a website.