I don't think dual core procesors are a problem in general. You can try setting the game to run on a specific core, and see if that makes a difference.
Monitoring and Optimizing Apps on Dual-Core and Multiprocessor Systems - briefly describes how to 'Set Affinity' of an application to a specific CPU through the Task Manager or using a couple other utilities.
So long to "Set Affinity"... - mentions another program to set CPU preference, as well as driver updates and an MS hotfix
