Well just to see how you people go for server should you decide to
either get a new one or further expand your hosting business. Intel Xeon or AMD Opteron?

Opteron tends to use less power than Xeon. However, Xeon will have more performance over Opteron.

A 4-socket server will either be a 16-cores Opteron or a 24-cores Xeon.

Xeon Dunnington which will be coming out later half this year will include 6 processing cores per chip.