Intel regularly holds Live Chat sessions where you can ask questions to their in-house experts on different emerging technologies. One such event solely on the new line of Core processors is slated to take place during the last week of February. I reckon you should put this question there for a complete answer. http://intellivechat.com/facebook.html
The operating system in a client OS tries to spread the task out the the physical processor first then the virtual ones, if you watch the load on a percore basis then the tend to jsut dance around over all the cores.
If you don't expect to be doing much in the way of heavy processing of video and the like, then and i5 with it's higher base speed and turbo will be a better match to your workloads.