WHy ? are you considering buying either ?
Besides, if a fair comparison between a PC and a Mac is already hard, comparing an Opteron to an Itanium system is 10x as hard. There are just too many criteria, completely different configuration, types of workloads, differences in OS, apps, complilers to make a comprehensive "itanium versus opteron" article. It would be meaningless and almost impossible.
= The views stated herein are my personal views, and not necessarily the views of my wife. =