A comparison of different types of processors is a rather technical area. But, there's really no need to get into such details for your situation. The reason is that the minimum requirement of a pentium 166 indicates a Penium running at 166MHz clock speed, or processor speed, which is far slower that the 1.8GHz (this equals 1,800MHz) Sempron 3100+. The 166MHz speed rating indicates an early Pentium (equals Pentium I), which preceeded Pentium II, Pentium III, and Pentium IV processors. In other words, a pentium 166 is a very old processor, while the Sempron 3100+ came onto the market much later, and even the first Sempron processors were much faster than that 166MHz Pentium.