Your English is fine.
And you were told right. Core i5-520m is, overall, better than the Phenom II X4 N970.
Did you realize the Elitebook 8440p has about double the battery life? 6.5hrs vs 3.5hrs.AMD Phenom II X4 N970 reviewIntel Core i5-520M reviewComparison of Mobile Processors (CPU Benchmarks)
Intel Core i5 520M is ranked #63
AMD Phenom II X4 N970 is ranked #92
In terms of ruggedness and reliability the business class Elitebook 8440p should have a convincing advantage over the consumer class Acer Aspire 5552.