I really like the size of the 13" MBP but the most powerful processor available is a dual core i7. I need to run a small Win 7 vm and a win 8.1 vm at the same time. The win8.1 vm must be fluid and appear to not be virtualized. The applications running will be fairly standard office desktop applications. On the OS X side I will need to record the running win 8.1 vm. Do you think I can use a 13" i7 dual core or do I need the 15" with quad core?