There is no one answer that will fit all situations. You're using the machines (desktop or laptop) with software that may or may not fully utilize the hardware capability. The best answer I can give would be to open up the task manager (assuming a Windows XP | Vista | 7) and track the performance for the various apps you use. Video will be heavy IO, CPU and GPU each contribute to speed. Tracking snap shots of performance and a variety of apps for the same data set may reveal the true differences between which processor will be suitable for the task.
There are probably benchmark apps that may help automate the testing process.