The test results speak for themselves. It's easy to see that Windows XP performs faster for all but 1 of the tests performed. As a total, with the Mushkin 2x1GB and Kingston 2x2GB memory configurations, the test suite ran 27% and 28%, respectively, faster with Windows XP than OSX. Not only does Windows XP beat OSX in Photoshop CS3 performance, but it demolishes it by a wide margin.
http://www.circuitremix.com/index.php?q=node/9
Anyone have any questions, suggestions or criticisms on the test or methods?