Rather small site architecture.

Website stats:

Webserver: Apache 2.2
Database: MySQL 5.0
APC cache for php
CMS: Drupal 6.2 (bleeding-edge version)*
*Aggressive caching is ON, Page Compression ON, Block Cache ON (can't use CCS),Optimize CSS/JS ON.
2 Servers: Apache/Mysql (low-tech servers - Celeron processors, 512 MB RAM, 7200 RPM HDD)
Bandwidth 10 Mb/s

The benchmark:

Used ab : ab -n 1000 -c 20 howwhatwho.com

Server Software:        Apache/2.2.3
Server Hostname:        howwhatwho.com
Server Port:            80
Document Path:          /
Document Length:        41639 bytes
Concurrency Level:      20
Time taken for tests:   13.556796 seconds
Complete requests:      1000
Failed requests:        0
Write errors:           0
Total transferred:      42118000 bytes
HTML transferred:       41639000 bytes
Requests per second:    73.76 [#/sec] (mean)
Time per request:       271.136 [ms] (mean)
Time per request:       13.557 [ms] (mean, across all concurrent requests)
Transfer rate:          3033.90 [Kbytes/sec] received

The Apache server is also running the postifx and bind although they aren't resource intensive applications.
The Cron job for drupal runs every 50 minutes, and the agreggator module is enabled and fetches more than 30 rss feeds every time.

The site used to be hosted on a single Celeron machine but on peak times the CPU went up to 80 %.

Question : Does anybody know a website hosted on an IBM Mainframe? :) Todd?