Right now I have a xeon quad core (2.8ghz I think), 8gb ram, and 150gb WD Raptor drive with centos.
We have a few sites that get around 600k page views and just under 10 million search engine bot crawls a month.
We've been using this setup for about 2 years now and haven't had a single problem yet, all pages load instantly. I'm not a hardcore server engineer, but when I do the "top" command in ssh there is alwasy ~10 httpd processes using between 0.5 - 5% cpu each and mysql using an average 15% cpu.
I'm tempted to replace apache with fastcgi to avoid apaches overhead, but I'm not sure what the ramifications might be such as security or stability or if it would even reduce cpu load.
Would this change be worth it?