1. An integrated method for validating the functionality and performance of software applications through multiple test phases using a common set of business requirements-based manual test scripts, the method comprising the steps of: identifying functional and technical requirements from the business requirements for the software application; deriving functional and technical test conditions in a functional test phase that are based on the identified functional and technical requirements; creating manual test scripts based on the functional and technical test conditions using a standard software testing tool accessed through a computer workstation, wherein the manual test scripts are created in the functional test phase; executing the manual test scripts and generating test results during the functional test phase using the standard software testing tool; selecting a first subset of manual test scripts from the manual test scripts that can be used to automate testing during an automated regression test phase; creating automated regression tests based on the first subset of manual test scripts, wherein creating automated regression tests comprises: reviewing screens used for each script from the first subset of manual test scripts; identifying object types on each of the screens; identifying actions for each object type identified on each of the screens; creating reusable functions for each action identified; identifying identifiers for each unique object of the identified object types; creating an XML (extensible markup language), object repository that contains reusable XML objects; creating reusable automated functions based on the reusable functions and the reusable XML objects; creating automated test scripts based on the reusable automated functions, and executing automated regression tests and generating test results during the automated regression test phase using the standard software testing tool.