The Windows Experience Index (WEI) scores are influenced by various factors, including clock speed, architecture, cache size, and other specifications of the processor. In your case, while both the E5200 dual-core processor and the Core 2 Duo E6420 are from the Core 2 Duo family, there are differences that could explain the drop in your WEI scores after the upgrade. Here are a few reasons why you might be observing a lower WEI score with the Core 2 Duo E6420 compared to the E5200 dual-core processor: 1. Clock Speed Difference: The clock speed alone does not determine the performance of a processor. The E5200 has a higher base clock speed of 2.5GHz compared to the E6420's 2.13GHz. In certain tasks that rely heavily on clock speed...