I want to know if there is a guide that shows how much ram each voip port requires, so if i have a system handling 120 conquering calls i can just calculate how fast will my system be. Also whats better for an asterisk system handling the same ammount of calls, a pentium d 830 or an amd X2 3800+. Thanks for the help. 
Have you read this? voip-info.org/wiki-Asterisk+dimensioning