Which Among these is a better processor for dedicated server Intel P4 2.8Ghz HT Intel Dual Core Atom Intel Dual Xeon 3Ghz Hyper Threaded
If those are your only choices then the last one although both the P4 and Xeon are a little old now. The atom is only for the most undemanding tasks and you won't save much money over getting a decent Xeon Quad Core.
Hello, Please have a look at http://www.cpubenchmark.net/ . This website give a good comparison results
Absolutely, the Intel Dual Xeon 3Ghz Hyper Threaded is more powerful and offers much more performance.