dual channel basically provides more memory bandwidth... in memory intensive situations this improves the overall amount of data that can be processed and reduces swap times effectively... end result can be an increase in speed
the athlon64 cpu's boards are single channel but in most situations you are not going to notice the difference...
there will be a socket 939 soon (april I think) that is dual channel/unbuffered and should probably also have pci-Ex...
the a64 cpus are x86-64... ergo they are effectively 32bit cpu's with 64bit extensions so they can run 32bit applications perfectly fine and in fact do so @ a greater speed than current x86 cpu's...
in 64 bit environment using 64bit extensions in some situations where there is no need for 64bit data chunks there may be a performance penalty in some situations but in general you are looking @ the same or increased performance in the neighborhood of around 5-30% or more performance improvement (I am going by inhouse numbers from people producing 64bit apps using amd's extensions)
p.s. mafia

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