I;ve viewed the posts. Which discribed why vista didn;t show the 2 processors. It said that go to msconfig->boot to enable HAL detect. But XP hasn't such thing.SO I have 2 question... 1.how to enable XP to detect 2 processors like vista? "numproc" isn;t work. 2.The real reason of why PD has no option to switch 1 or 2 processor. I;d like to recieve the Admin's answer,which must be the offcial answer.