1. A system for providing usability predictions, comprising: a test case collector for obtaining test cases for analyzing usability of a graphical user interface of a given software application, the test case collector having at least a memory storing the test cases; a human performance model generator for automatically generating a human performance model based on the test cases; a usability predictor for generating the usability predictions based on the human performance model; and a rule generator for generating a set of rules that semantically refines one or more tasks applicable to the graphical user interface, wherein said test case collector automatically generates at least some of the test cases from an analysis of the given software application.