this anandtech article has tests and info of a dual opteron 248 (running @ 2.2Gz) V a Dual 2.8Gz Xeon as a webserver. They test twin 244 and 248 (1.8 and 2.2Gz respectivally) Opterons with 4Gb ram. the test is run on windows 2003 server with iis6 and coldfusion. check the article for more.