Hi,
I wonder how does asterisk benefits from the dual core processors or all simply, he does not use it because he is monothreaded?!!
FYI, i have done StressTest on asterisk on two machines : the first one was an Intel P4 and the second one was an Intel core 2 duo ,
conclusion : Number of call from one sip end to an other sip end was bigger in the first machine (Intel P4) than in the other one (Intel dual core)
Iām waiting for your responses, 
Sara